convert/mtn: convert suspended branches as closed branches
Monotone treats branch closing ("suspending") in a similar manner to how we do
in mercurial - a cert is added to a revision that marks the branch to be hidden.
If a subsequent commit is made, the branch is effectively reopened.
rebase: don't mark file as removed if missing in parent's manifest (
issue2725)
windows: use win32.unlink in unlinkpath()
os.unlink fails to remove files with READONLY attribute