test-rebase-base: clarify it is about the "--base" flag

It happened several times that people use `test-rebase-base.t` as a general
purposed test file for rebase. But it is intended to be only related to the
`--base` flag. This patch split, renamed the test, and added a note to
clarify.

Differential Revision: https://phab.mercurial-scm.org/D975

tests/test-rebase-base-flag.t

@@ -1,3 +1,6 @@
+Test the "--base" flag of the rebase command. (Tests unrelated to the "--base"
+flag should probably live in somewhere else)
+
   $ cat >> $HGRCPATH <<EOF
   > [extensions]
   > rebase=
@@ -379,40 +382,3 @@ Multiple roots. Two children share two parents while dest has only one parent:
    /
   o  0: A
   
-Rebasing using a single transaction
-
-  $ hg init singletr && cd singletr
-  $ cat >> .hg/hgrc <<EOF
-  > [rebase]
-  > singletransaction=True
-  > EOF
-  $ hg debugdrawdag <<'EOF'
-  >   Z
-  >   |
-  >   | D
-  >   | |
-  >   | C
-  >   | |
-  >   Y B
-  >   |/
-  >   A
-  > EOF
-- We should only see two status stored messages. One from the start, one from
-- the end.
-  $ hg rebase --debug -b D -d Z | grep 'status stored'
-  rebase status stored
-  rebase status stored
-  $ hg tglog
-  o  5: D
-  |
-  o  4: C
-  |
-  o  3: B
-  |
-  o  2: Z
-  |
-  o  1: Y
-  |
-  o  0: A
-  
-  $ cd ..

tests/test-rebase-transaction.t

@@ -0,0 +1,49 @@
+  $ cat >> $HGRCPATH <<EOF
+  > [extensions]
+  > rebase=
+  > drawdag=$TESTDIR/drawdag.py
+  > 
+  > [phases]
+  > publish=False
+  > 
+  > [alias]
+  > tglog = log -G --template "{rev}: {desc}"
+  > EOF
+
+Rebasing using a single transaction
+
+  $ hg init singletr && cd singletr
+  $ cat >> .hg/hgrc <<EOF
+  > [rebase]
+  > singletransaction=True
+  > EOF
+  $ hg debugdrawdag <<'EOF'
+  >   Z
+  >   |
+  >   | D
+  >   | |
+  >   | C
+  >   | |
+  >   Y B
+  >   |/
+  >   A
+  > EOF
+- We should only see two status stored messages. One from the start, one from
+- the end.
+  $ hg rebase --debug -b D -d Z | grep 'status stored'
+  rebase status stored
+  rebase status stored
+  $ hg tglog
+  o  5: D
+  |
+  o  4: C
+  |
+  o  3: B
+  |
+  o  2: Z
+  |
+  o  1: Y
+  |
+  o  0: A
+  
+  $ cd ..