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 dir/bar
adding foo
dir/bar
foo
committed changeset 0:d44511117907
adding dir/bar_2
adding foo_2
dir/bar_2
foo_2
committed changeset 1:a85812e0561a
adding a
adding c
removing a
adding b
removing c
adding d
recording removal of a as rename to b (100% similar)
removing a
adding b
removing c
adding d
recording removal of a as rename to b (100% similar)