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
comparing with l://
searching for changes
no changes found
% check that {1} syntax works
using http://localhost:/
sending between command
comparing with parts://localhost
sending heads command
searching for changes
no changes found
% errors