[#349532] possibly easy win32 bug -- bzr always returns exit code 0

[Martin Pool]

I thought someone more expert on win32 could look into
https://bugs.edge.launchpad.net/bzr/+bug/349532 -- bzr always
apparently gives back a status code of 0 to the OS, even when we try
to indicate an error.  Even just identifying whether this is
particular to this one user or not would be useful.

-- 
Martin <http://launchpad.net/~mbp/>