tests/test-bundle-vs-outgoing.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.

% setup test repo1
adding foo.txt
rev 1
rev 2
rev 3
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
rev 4
rev 5
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
rev 7
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
rev 8
% the story so far
@  8
|
| o  7
| |
| o  6
|/|
o |  5
| |
o |  4
| |
| o  3
| |
| o  2
|/
o  1
|
o  0

% sanity check of outgoing: expect revs 4 5 6 7 8
requesting all changes
adding changesets
adding manifests
adding file changes
added 4 changesets with 4 changes to 1 files
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
comparing with ../repo2
searching for changes
4
5
6
7
8
% test bundle (destination repo): expect 5 revisions
searching for changes
5 changesets found
% test bundle (base revision): expect 5 revisions
5 changesets found