$ git clone -n https://src.fedoraproject.org/rpms/muffin.git /var/lib/mock/f40-build-755761-118394/root/chroot_tmpdir/scmroot/muffin
Cloning into '/var/lib/mock/f40-build-755761-118394/root/chroot_tmpdir/scmroot/muffin'...
$ git fetch origin cf7e70a66d29e7f664e02216de7ce72edb0de398:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/muffin
 * [new ref]         cf7e70a66d29e7f664e02216de7ce72edb0de398 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cf7e70a Drop eglstreams support