$ git clone -n https://src.fedoraproject.org/rpms/buildbot.git /var/lib/mock/f40-build-2074228-49392/root/chroot_tmpdir/scmroot/buildbot
Cloning into '/var/lib/mock/f40-build-2074228-49392/root/chroot_tmpdir/scmroot/buildbot'...
$ git fetch origin 3ea1f527c7913390c59a82d773070d0e7cf5b96a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/buildbot
 * [new ref]         3ea1f527c7913390c59a82d773070d0e7cf5b96a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3ea1f52 3.10.0