$ git clone -n https://src.fedoraproject.org/rpms/xz.git /var/lib/mock/f41-build-side-1-2810831-32921/root/chroot_tmpdir/scmroot/xz
Cloning into '/var/lib/mock/f41-build-side-1-2810831-32921/root/chroot_tmpdir/scmroot/xz'...
$ git fetch origin af339afd3c1df228138de25c0d8f89ad7c773212:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xz
 * [new ref]         af339afd3c1df228138de25c0d8f89ad7c773212 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at af339af New upstream version 5.6.3 (RHBZ#2316069)