$ git clone -n https://src.fedoraproject.org/rpms/muffin.git /var/lib/mock/f45-build-19319-547/root/chroot_tmpdir/scmroot/muffin
Cloning into '/var/lib/mock/f45-build-19319-547/root/chroot_tmpdir/scmroot/muffin'...
$ git fetch origin c4d142c0c0ae43e58d4eca5d152197ee6d7b9d7b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/muffin
 * [new ref]         c4d142c0c0ae43e58d4eca5d152197ee6d7b9d7b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c4d142c Update to 6.7.7-unstable