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.
abort: uncommitted local changes
dirty
M foo
% validate update of standalone execute bit change
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
nothing changed
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
0 files updated, 0 files merged, 0 files removed, 0 files unresolved