$ git clone -n https://src.fedoraproject.org/rpms/trellis.git /var/lib/mock/f39-build-1526978-36115/root/chroot_tmpdir/scmroot/trellis
Cloning into '/var/lib/mock/f39-build-1526978-36115/root/chroot_tmpdir/scmroot/trellis'...
$ git fetch origin bc5b17ff639e89f529526ecf4246964ad73ab015:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/trellis
 * [new ref]         bc5b17ff639e89f529526ecf4246964ad73ab015 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bc5b17f update to newer snapshot