Branch push scheduler
Branch push scheduler

The branch push scheduler should use the stock SingleBranchScheduler.
This ensures it always builds against the latest master source for
the various codebases.

Signed-off-by: Brian Behlendorf <32d50ad1e384dcb9a5bf7e40fa470df5dabaf348@llnl.gov>

zfsonlinux/zfs-buildbot,zfsonlinux/zfs-buildbot,gmelikov/zfs-buildbot,gmelikov/zfs-buildbot