$ git clone -n https://src.fedoraproject.org/rpms/papers.git /var/lib/mock/f42-build-3363762-45042/root/chroot_tmpdir/scmroot/papers
Cloning into '/var/lib/mock/f42-build-3363762-45042/root/chroot_tmpdir/scmroot/papers'...
$ git fetch origin a879ad0cd169eedf5471aa35ab96aacddaf91c96:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/papers
 * [new ref]         a879ad0cd169eedf5471aa35ab96aacddaf91c96 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a879ad0 v48 RC release