tests/test-merge4.t

rebase: clear updatestate during rebase --abort in more cases

Previously, rebase --abort would only call update if you were on a node that had
already been rebased. This meant that if the rebase failed during the rebase of
the first commit, the working copy would be left dirty (with a .hg/updatestate
file) and rebase --abort would not have update to clean it up.

The fix is to also perform an update if you're still on the target node or on
the original working copy node (since the working copy may be dirty, we still
need to do the update). We don't want to perform an update in all cases though
because of issue4009.

A subsequent patch makes this case much more common, since it causes the entire
rebase transaction to rollback during unexpected exceptions. This causes the
existing test-rebase-abort.t to cover this case.

  $ hg init
  $ echo This is file a1 > a
  $ hg add a
  $ hg commit -m "commit #0"
  $ echo This is file b1 > b
  $ hg add b
  $ hg commit -m "commit #1"
  $ hg update 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo This is file c1 > c
  $ hg add c
  $ hg commit -m "commit #2"
  created new head
  $ hg merge 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ rm b
  $ echo This is file c22 > c

Test hg behaves when committing with a missing file added by a merge

  $ hg commit -m "commit #3"
  abort: cannot commit merge with missing files
  [255]