prepush: add more precise error messages
Part of the patch is from timeless@mozdev.org
- 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.
adding a
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
% should issue warning
adding a
created new head
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
% should not issue warning
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
marked working directory as branch testing
% should not issue warning