tests/test-branchmap.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.

marked working directory as branch æ
adding foo
listening at http://localhost/ (bound to 127.0.0.1)
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
updating to branch æ
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
changeset:   0:867c11ce77b8
branch:      æ
tag:         tip
user:        test
date:        Thu Jan 01 00:00:00 1970 +0000
summary:     foo

pushing to http://localhost:PORT
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
changeset:   1:58e7c90d67cb
branch:      æ
tag:         tip
user:        test
date:        Thu Jan 01 00:00:00 1970 +0000
summary:     bar

changeset:   0:867c11ce77b8
branch:      æ
user:        test
date:        Thu Jan 01 00:00:00 1970 +0000
summary:     foo

pushing to ssh://dummy/
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files