$ git clone -n https://src.fedoraproject.org/rpms/Maelstrom.git /var/lib/mock/f40-build-2009920-45537/root/chroot_tmpdir/scmroot/Maelstrom
Cloning into '/var/lib/mock/f40-build-2009920-45537/root/chroot_tmpdir/scmroot/Maelstrom'...
$ git fetch origin 73aca9f79dab2a2484d5f81e46fff543bf62ed0a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/Maelstrom
 * [new ref]         73aca9f79dab2a2484d5f81e46fff543bf62ed0a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 73aca9f Stop building for i686