jj/lib/tests/test_mut_repo.rs

// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use jujutsu_lib::commit_builder::CommitBuilder;
use jujutsu_lib::op_store::{RefTarget, WorkspaceId};
use jujutsu_lib::testutils;
use jujutsu_lib::testutils::{assert_rebased, CommitGraphBuilder};
use maplit::hashset;
use test_case::test_case;

// TODO Many of the tests here are not run with Git because they end up creating
// two commits with the same contents.

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_checkout_open(use_git: bool) {
    // Test that MutableRepo::check_out() uses the requested commit if it's open
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let requested_checkout = testutils::create_random_commit(&settings, repo)
        .set_open(true)
        .write_to_repo(tx.mut_repo());
    let repo = tx.commit();

    let mut tx = repo.start_transaction("test");
    let ws_id = WorkspaceId::default();
    let actual_checkout = tx
        .mut_repo()
        .check_out(ws_id.clone(), &settings, &requested_checkout);
    assert_eq!(actual_checkout.id(), requested_checkout.id());
    let repo = tx.commit();
    assert_eq!(repo.view().get_checkout(&ws_id), Some(actual_checkout.id()));
}

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_checkout_closed(use_git: bool) {
    // Test that MutableRepo::check_out() creates a child if the requested commit is
    // closed
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let requested_checkout = testutils::create_random_commit(&settings, repo)
        .set_open(false)
        .write_to_repo(tx.mut_repo());
    let repo = tx.commit();

    let mut tx = repo.start_transaction("test");
    let ws_id = WorkspaceId::default();
    let actual_checkout = tx
        .mut_repo()
        .check_out(ws_id.clone(), &settings, &requested_checkout);
    assert_eq!(actual_checkout.tree_id(), requested_checkout.tree_id());
    assert_eq!(actual_checkout.parents().len(), 1);
    assert_eq!(actual_checkout.parents()[0].id(), requested_checkout.id());
    let repo = tx.commit();
    assert_eq!(repo.view().get_checkout(&ws_id), Some(actual_checkout.id()));
}

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_checkout_previous_not_empty(use_git: bool) {
    // Test that MutableRepo::check_out() does not usually abandon the previous
    // commit.
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    let old_checkout = testutils::create_random_commit(&settings, repo)
        .set_open(true)
        .write_to_repo(mut_repo);
    let ws_id = WorkspaceId::default();
    mut_repo.check_out(ws_id.clone(), &settings, &old_checkout);
    let repo = tx.commit();

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    let new_checkout = testutils::create_random_commit(&settings, &repo)
        .set_open(true)
        .write_to_repo(mut_repo);
    mut_repo.check_out(ws_id, &settings, &new_checkout);
    mut_repo.rebase_descendants(&settings);
    assert!(mut_repo.view().heads().contains(old_checkout.id()));
}

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_checkout_previous_empty(use_git: bool) {
    // Test that MutableRepo::check_out() abandons the previous commit if it was
    // empty.
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    let old_checkout = CommitBuilder::for_open_commit(
        &settings,
        repo.store(),
        repo.store().root_commit_id().clone(),
        repo.store().empty_tree_id().clone(),
    )
    .write_to_repo(mut_repo);
    let ws_id = WorkspaceId::default();
    mut_repo.check_out(ws_id.clone(), &settings, &old_checkout);
    let repo = tx.commit();

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    let new_checkout = testutils::create_random_commit(&settings, &repo)
        .set_open(true)
        .write_to_repo(mut_repo);
    mut_repo.check_out(ws_id, &settings, &new_checkout);
    mut_repo.rebase_descendants(&settings);
    assert!(!mut_repo.view().heads().contains(old_checkout.id()));
}

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_checkout_previous_empty_non_head(use_git: bool) {
    // Test that MutableRepo::check_out() does not abandon the previous commit if it
    // was empty and is not a head
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    let old_checkout = CommitBuilder::for_open_commit(
        &settings,
        repo.store(),
        repo.store().root_commit_id().clone(),
        repo.store().empty_tree_id().clone(),
    )
    .write_to_repo(mut_repo);
    let old_child = CommitBuilder::for_open_commit(
        &settings,
        repo.store(),
        old_checkout.id().clone(),
        old_checkout.tree_id().clone(),
    )
    .write_to_repo(mut_repo);
    let ws_id = WorkspaceId::default();
    mut_repo.check_out(ws_id.clone(), &settings, &old_checkout);
    let repo = tx.commit();

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    let new_checkout = testutils::create_random_commit(&settings, &repo)
        .set_open(true)
        .write_to_repo(mut_repo);
    mut_repo.check_out(ws_id, &settings, &new_checkout);
    mut_repo.rebase_descendants(&settings);
    assert_eq!(
        *mut_repo.view().heads(),
        hashset! {old_child.id().clone(), new_checkout.id().clone()}
    );
}

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_checkout_initial(use_git: bool) {
    // Test that MutableRepo::check_out() can be used on the initial checkout in a
    // workspace
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let requested_checkout = testutils::create_random_commit(&settings, repo)
        .set_open(true)
        .write_to_repo(tx.mut_repo());
    let repo = tx.commit();

    let mut tx = repo.start_transaction("test");
    let workspace_id = WorkspaceId::new("new-workspace".to_string());
    let actual_checkout =
        tx.mut_repo()
            .check_out(workspace_id.clone(), &settings, &requested_checkout);
    assert_eq!(actual_checkout.id(), requested_checkout.id());
    let repo = tx.commit();
    assert_eq!(
        repo.view().get_checkout(&workspace_id),
        Some(actual_checkout.id())
    );
}

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_add_head_success(use_git: bool) {
    // Test that MutableRepo::add_head() adds the head, and that it's still there
    // after commit. It should also be indexed.
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    // Create a commit outside of the repo by using a temporary transaction. Then
    // add that as a head.
    let mut tx = repo.start_transaction("test");
    let new_commit = testutils::create_random_commit(&settings, repo).write_to_repo(tx.mut_repo());
    drop(tx);

    let index_stats = repo.index().stats();
    assert_eq!(index_stats.num_heads, 1);
    assert_eq!(index_stats.num_commits, 1);
    assert_eq!(index_stats.max_generation_number, 0);
    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    assert!(!mut_repo.view().heads().contains(new_commit.id()));
    assert!(!mut_repo.index().has_id(new_commit.id()));
    mut_repo.add_head(&new_commit);
    assert!(mut_repo.view().heads().contains(new_commit.id()));
    assert!(mut_repo.index().has_id(new_commit.id()));
    let repo = tx.commit();
    assert!(repo.view().heads().contains(new_commit.id()));
    assert!(repo.index().has_id(new_commit.id()));
    let index_stats = repo.index().stats();
    assert_eq!(index_stats.num_heads, 1);
    assert_eq!(index_stats.num_commits, 2);
    assert_eq!(index_stats.max_generation_number, 1);
}

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_add_head_ancestor(use_git: bool) {
    // Test that MutableRepo::add_head() does not add a head if it's an ancestor of
    // an existing head.
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let mut graph_builder = CommitGraphBuilder::new(&settings, tx.mut_repo());
    let commit1 = graph_builder.initial_commit();
    let commit2 = graph_builder.commit_with_parents(&[&commit1]);
    let _commit3 = graph_builder.commit_with_parents(&[&commit2]);
    let repo = tx.commit();

    let index_stats = repo.index().stats();
    assert_eq!(index_stats.num_heads, 1);
    assert_eq!(index_stats.num_commits, 4);
    assert_eq!(index_stats.max_generation_number, 3);
    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    mut_repo.add_head(&commit1);
    assert!(!mut_repo.view().heads().contains(commit1.id()));
    let index_stats = mut_repo.index().stats();
    assert_eq!(index_stats.num_heads, 1);
    assert_eq!(index_stats.num_commits, 4);
    assert_eq!(index_stats.max_generation_number, 3);
}

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_add_head_not_immediate_child(use_git: bool) {
    // Test that MutableRepo::add_head() can be used for adding a head that is not
    // an immediate child of a current head.
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let initial = testutils::create_random_commit(&settings, repo).write_to_repo(tx.mut_repo());
    let repo = tx.commit();

    // Create some commit outside of the repo by using a temporary transaction. Then
    // add one of them as a head.
    let mut tx = repo.start_transaction("test");
    let rewritten = testutils::create_random_commit(&settings, &repo)
        .set_change_id(initial.change_id().clone())
        .set_predecessors(vec![initial.id().clone()])
        .write_to_repo(tx.mut_repo());
    let child = testutils::create_random_commit(&settings, &repo)
        .set_parents(vec![rewritten.id().clone()])
        .write_to_repo(tx.mut_repo());
    drop(tx);

    let index_stats = repo.index().stats();
    assert_eq!(index_stats.num_heads, 1);
    assert_eq!(index_stats.num_commits, 2);
    assert_eq!(index_stats.max_generation_number, 1);
    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    mut_repo.add_head(&child);
    assert!(mut_repo.view().heads().contains(initial.id()));
    assert!(!mut_repo.view().heads().contains(rewritten.id()));
    assert!(mut_repo.view().heads().contains(child.id()));
    assert!(mut_repo.index().has_id(initial.id()));
    assert!(mut_repo.index().has_id(rewritten.id()));
    assert!(mut_repo.index().has_id(child.id()));
    let index_stats = mut_repo.index().stats();
    assert_eq!(index_stats.num_heads, 2);
    assert_eq!(index_stats.num_commits, 4);
    assert_eq!(index_stats.max_generation_number, 2);
}

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_remove_head(use_git: bool) {
    // Test that MutableRepo::remove_head() removes the head, and that it's still
    // removed after commit. It should remain in the index, since we otherwise would
    // have to reindex everything.
    // TODO: Consider if it's better to have the index be exactly the commits
    // reachable from the view's heads. We would probably want to add tombstones
    // for commits no longer visible in that case so we don't have to reindex e.g.
    // when the user does `jj op undo`.
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let mut graph_builder = CommitGraphBuilder::new(&settings, tx.mut_repo());
    let commit1 = graph_builder.initial_commit();
    let commit2 = graph_builder.commit_with_parents(&[&commit1]);
    let commit3 = graph_builder.commit_with_parents(&[&commit2]);
    let repo = tx.commit();

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    assert!(mut_repo.view().heads().contains(commit3.id()));
    mut_repo.remove_head(commit3.id());
    let heads = mut_repo.view().heads().clone();
    assert!(!heads.contains(commit3.id()));
    assert!(!heads.contains(commit2.id()));
    assert!(!heads.contains(commit1.id()));
    assert!(mut_repo.index().has_id(commit1.id()));
    assert!(mut_repo.index().has_id(commit2.id()));
    assert!(mut_repo.index().has_id(commit3.id()));
    let repo = tx.commit();
    let heads = repo.view().heads().clone();
    assert!(!heads.contains(commit3.id()));
    assert!(!heads.contains(commit2.id()));
    assert!(!heads.contains(commit1.id()));
    assert!(repo.index().has_id(commit1.id()));
    assert!(repo.index().has_id(commit2.id()));
    assert!(repo.index().has_id(commit3.id()));
}

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_add_public_head(use_git: bool) {
    // Test that MutableRepo::add_public_head() adds the head, and that it's still
    // there after commit.
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let commit1 = testutils::create_random_commit(&settings, repo).write_to_repo(tx.mut_repo());
    let repo = tx.commit();

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    assert!(!mut_repo.view().public_heads().contains(commit1.id()));
    mut_repo.add_public_head(&commit1);
    assert!(mut_repo.view().public_heads().contains(commit1.id()));
    let repo = tx.commit();
    assert!(repo.view().public_heads().contains(commit1.id()));
}

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_add_public_head_ancestor(use_git: bool) {
    // Test that MutableRepo::add_public_head() does not add a public head if it's
    // an ancestor of an existing public head.
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let mut graph_builder = CommitGraphBuilder::new(&settings, tx.mut_repo());
    let commit1 = graph_builder.initial_commit();
    let commit2 = graph_builder.commit_with_parents(&[&commit1]);
    tx.mut_repo().add_public_head(&commit2);
    let repo = tx.commit();

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    assert!(!mut_repo.view().public_heads().contains(commit1.id()));
    mut_repo.add_public_head(&commit1);
    assert!(!mut_repo.view().public_heads().contains(commit1.id()));
    let repo = tx.commit();
    assert!(!repo.view().public_heads().contains(commit1.id()));
}

#[test_case(false ; "local backend")]
// #[test_case(true ; "git backend")]
fn test_remove_public_head(use_git: bool) {
    // Test that MutableRepo::remove_public_head() removes the head, and that it's
    // still removed after commit.
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    let commit1 = testutils::create_random_commit(&settings, repo).write_to_repo(mut_repo);
    mut_repo.add_public_head(&commit1);
    let repo = tx.commit();

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    assert!(mut_repo.view().public_heads().contains(commit1.id()));
    mut_repo.remove_public_head(commit1.id());
    assert!(!mut_repo.view().public_heads().contains(commit1.id()));
    let repo = tx.commit();
    assert!(!repo.view().public_heads().contains(commit1.id()));
}

#[test_case(false ; "local backend")]
#[test_case(true ; "git backend")]
fn test_has_changed(use_git: bool) {
    // Test that MutableRepo::has_changed() reports changes iff the view has changed
    // (e.g. not after setting a branch to point to where it was already
    // pointing).
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    let commit1 = testutils::create_random_commit(&settings, repo).write_to_repo(mut_repo);
    let commit2 = testutils::create_random_commit(&settings, repo).write_to_repo(mut_repo);
    mut_repo.remove_head(commit2.id());
    mut_repo.add_public_head(&commit1);
    let ws_id = WorkspaceId::default();
    mut_repo.set_checkout(ws_id.clone(), commit1.id().clone());
    mut_repo.set_local_branch("main".to_string(), RefTarget::Normal(commit1.id().clone()));
    mut_repo.set_remote_branch(
        "main".to_string(),
        "origin".to_string(),
        RefTarget::Normal(commit1.id().clone()),
    );
    let repo = tx.commit();
    // Test the setup
    assert_eq!(repo.view().heads(), &hashset! {commit1.id().clone()});
    assert_eq!(repo.view().public_heads(), &hashset! {commit1.id().clone()});

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();

    mut_repo.add_public_head(&commit1);
    mut_repo.add_head(&commit1);
    mut_repo.set_checkout(ws_id.clone(), commit1.id().clone());
    mut_repo.set_local_branch("main".to_string(), RefTarget::Normal(commit1.id().clone()));
    mut_repo.set_remote_branch(
        "main".to_string(),
        "origin".to_string(),
        RefTarget::Normal(commit1.id().clone()),
    );
    assert!(!mut_repo.has_changes());

    mut_repo.remove_public_head(commit2.id());
    mut_repo.remove_head(commit2.id());
    mut_repo.remove_local_branch("stable");
    mut_repo.remove_remote_branch("stable", "origin");
    assert!(!mut_repo.has_changes());

    mut_repo.add_head(&commit2);
    assert!(mut_repo.has_changes());
    mut_repo.remove_head(commit2.id());
    assert!(!mut_repo.has_changes());

    mut_repo.add_public_head(&commit2);
    assert!(mut_repo.has_changes());
    mut_repo.remove_public_head(commit2.id());
    // The commit was added as a visible head when we called has_changes() above.
    // That's a weird side-effect.
    // TODO: Should we make add_public_head() also add it as a visible head? Or
    // should we decouple the two sets completely?
    mut_repo.remove_head(commit2.id());
    assert!(!mut_repo.has_changes());

    mut_repo.set_checkout(ws_id.clone(), commit2.id().clone());
    assert!(mut_repo.has_changes());
    mut_repo.set_checkout(ws_id, commit1.id().clone());
    assert!(!mut_repo.has_changes());

    mut_repo.set_local_branch("main".to_string(), RefTarget::Normal(commit2.id().clone()));
    assert!(mut_repo.has_changes());
    mut_repo.set_local_branch("main".to_string(), RefTarget::Normal(commit1.id().clone()));
    assert!(!mut_repo.has_changes());

    mut_repo.set_remote_branch(
        "main".to_string(),
        "origin".to_string(),
        RefTarget::Normal(commit2.id().clone()),
    );
    assert!(mut_repo.has_changes());
    mut_repo.set_remote_branch(
        "main".to_string(),
        "origin".to_string(),
        RefTarget::Normal(commit1.id().clone()),
    );
    assert!(!mut_repo.has_changes());
}

#[test_case(false ; "local backend")]
#[test_case(true ; "git backend")]
fn test_rebase_descendants_simple(use_git: bool) {
    // Tests that MutableRepo::create_descendant_rebaser() creates a
    // DescendantRebaser that rebases descendants of rewritten and abandoned
    // commits.
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let mut graph_builder = CommitGraphBuilder::new(&settings, tx.mut_repo());
    let commit1 = graph_builder.initial_commit();
    let commit2 = graph_builder.commit_with_parents(&[&commit1]);
    let commit3 = graph_builder.commit_with_parents(&[&commit2]);
    let commit4 = graph_builder.commit_with_parents(&[&commit1]);
    let commit5 = graph_builder.commit_with_parents(&[&commit4]);
    let repo = tx.commit();

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    let mut graph_builder = CommitGraphBuilder::new(&settings, mut_repo);
    let commit6 = graph_builder.commit_with_parents(&[&commit1]);
    mut_repo.record_rewritten_commit(commit2.id().clone(), commit6.id().clone());
    mut_repo.record_abandoned_commit(commit4.id().clone());
    let mut rebaser = mut_repo.create_descendant_rebaser(&settings);
    // Commit 3 got rebased onto commit 2's replacement, i.e. commit 6
    assert_rebased(rebaser.rebase_next(), &commit3, &[&commit6]);
    // Commit 5 got rebased onto commit 4's parent, i.e. commit 1
    assert_rebased(rebaser.rebase_next(), &commit5, &[&commit1]);
    assert!(rebaser.rebase_next().is_none());
    // No more descendants to rebase if we try again.
    assert!(mut_repo
        .create_descendant_rebaser(&settings)
        .rebase_next()
        .is_none());
}

#[test_case(false ; "local backend")]
#[test_case(true ; "git backend")]
fn test_rebase_descendants_conflicting_rewrite(use_git: bool) {
    // Tests MutableRepo::create_descendant_rebaser() when a commit has been marked
    // as rewritten to several other commits.
    let settings = testutils::user_settings();
    let test_repo = testutils::init_repo(&settings, use_git);
    let repo = &test_repo.repo;

    let mut tx = repo.start_transaction("test");
    let mut graph_builder = CommitGraphBuilder::new(&settings, tx.mut_repo());
    let commit1 = graph_builder.initial_commit();
    let commit2 = graph_builder.commit_with_parents(&[&commit1]);
    let _commit3 = graph_builder.commit_with_parents(&[&commit2]);
    let repo = tx.commit();

    let mut tx = repo.start_transaction("test");
    let mut_repo = tx.mut_repo();
    let mut graph_builder = CommitGraphBuilder::new(&settings, mut_repo);
    let commit4 = graph_builder.commit_with_parents(&[&commit1]);
    let commit5 = graph_builder.commit_with_parents(&[&commit1]);
    mut_repo.record_rewritten_commit(commit2.id().clone(), commit4.id().clone());
    mut_repo.record_rewritten_commit(commit2.id().clone(), commit5.id().clone());
    let mut rebaser = mut_repo.create_descendant_rebaser(&settings);
    // Commit 3 does *not* get rebased because it's unclear if it should go onto
    // commit 4 or commit 5
    assert!(rebaser.rebase_next().is_none());
    // No more descendants to rebase if we try again.
    assert!(mut_repo
        .create_descendant_rebaser(&settings)
        .rebase_next()
        .is_none());
}