If the working dir parent was destroyed by rollback, then the old
behaviour is perfectly reasonable: restore dirstate, branch, and
bookmarks. That way the working dir moves back to an existing
changeset rather than becoming an orphan.
But if the working dir parent was unaffected -- say, you updated to an
older changeset and then did rollback -- then it's silly to restore
dirstate and branch. So don't do that. Leave the status of the working
dir alone. (But always restore bookmarks, because that file refers to
changeset IDs that may have been destroyed.)
Previously, when rolling back a transaction, some users could be confused
between the level to which the store is rolled back, and the new parents
of the working directory.
$ hg rollback
rolling back to revision 4 (undo commit)
With this change:
$ hg rollback
repository tip rolled back to tip revision 4 (undo commit)
working directory now based on revision 2 and 1
So now the user can realize that the store has been rolled back to an older
tip, but also that the working directory may not on the tip (here we are
rolling back the merge of the heads 2 and 1)
