$ git clone -n https://src.fedoraproject.org/rpms/matrix-synapse.git /var/lib/mock/f41-build-side-1-3137961-39809/root/chroot_tmpdir/scmroot/matrix-synapse
Cloning into '/var/lib/mock/f41-build-side-1-3137961-39809/root/chroot_tmpdir/scmroot/matrix-synapse'...
$ git fetch origin ef3ab8bb3b314e34e4870bf895317fd35acb1a33:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/matrix-synapse
 * [new ref]         ef3ab8bb3b314e34e4870bf895317fd35acb1a33 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ef3ab8b 1.118.0