testing mirror push "one plus one" mode... (read below)
Currently, every time someone does a push to a master server, a slave push
(one for each slave) is triggered.
This is not only wasteful, it also causes too much load. First of all, pushes
should be serialised -- there is no point running TWO 'git push --mirror' from
one server to another. This means when one push is running, any more pushes
of the same repo to the same slave must be queued.
But more importantly, it does not make sense to queue more than one!
Hence the "one(running) plus one(queued)" name of the helper script.