tests/test-rebase-interruptions.out

prepush: add more precise error messages

Part of the patch is from [e-mail]

- indicate the branch name where there are multiple heads
- give better advice when hitting a possible race, where new heads are added
  between discovery and the call to branchmap(). In that case, asking the user
  to merge isn't helpful, since only remote has the changes.

% Changes during an interruption - continue
@  4: E
|
o  3: D
|
| o  2: C
| |
| o  1: B
|/
o  0: A


% - Rebasing B onto E
merging A
warning: conflicts during merge.
merging A failed!
abort: fix unresolved conflicts with hg resolve then run hg rebase --continue

% - Force a commit on C during the interruption
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
@  6: Extra
|
| o  5: B
| |
| o  4: E
| |
| o  3: D
| |
o |  2: C
| |
o |  1: B
|/
o  0: A


% - Resume the rebasing
merging A
warning: conflicts during merge.
merging A failed!
abort: fix unresolved conflicts with hg resolve then run hg rebase --continue

% - Solve the conflict and go on
warning: new changesets detected on source branch, not stripping
rebase completed
@  7: C
|
| o  6: Extra
| |
o |  5: B
| |
o |  4: E
| |
o |  3: D
| |
| o  2: C
| |
| o  1: B
|/
o  0: A



% Changes during an interruption - abort
@  4: E
|
o  3: D
|
| o  2: C
| |
| o  1: B
|/
o  0: A


% Rebasing B onto E
merging A
warning: conflicts during merge.
merging A failed!
abort: fix unresolved conflicts with hg resolve then run hg rebase --continue

% Force a commit on B' during the interruption
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
@  6: Extra
|
o  5: B
|
o  4: E
|
o  3: D
|
| o  2: C
| |
| o  1: B
|/
o  0: A


% Abort the rebasing
warning: new changesets detected on target branch, not stripping
@  6: Extra
|
o  5: B
|
o  4: E
|
o  3: D
|
| o  2: C
| |
| o  1: B
|/
o  0: A