tests/test-rollback.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.

checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
changeset:   0:0acdaf898367
tag:         tip
user:        test
date:        Mon Jan 12 13:46:40 1970 +0000
summary:     test

rolling back last transaction
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
0 files, 0 changesets, 0 total revisions
A a
% Test issue 902
marked working directory as branch test
rolling back last transaction
default
% Test issue 1635 (commit message saved)
.hg/last-message.txt:
test2
% Test rollback of hg before issue 902 was fixed
marked working directory as branch test
rolling back last transaction
Named branch could not be reset, current branch still is: test
test
% rollback by pretxncommit saves commit message (issue 1635)
transaction abort!
rollback completed
abort: pretxncommit hook exited ...
.hg/last-message.txt:
precious commit message
% same thing, but run $EDITOR
transaction abort!
rollback completed
note: commit message saved in .hg/last-message.txt
abort: pretxncommit hook exited ...
.hg/last-message.txt:
another precious commit message