$ git clone -n https://src.fedoraproject.org/rpms/brewtarget.git /var/lib/mock/f42-build-862897-171231/root/chroot_tmpdir/scmroot/brewtarget
Cloning into '/var/lib/mock/f42-build-862897-171231/root/chroot_tmpdir/scmroot/brewtarget'...
$ git fetch origin 5870b0eb74e1ec2712d4e198c0cface03134678a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/brewtarget
 * [new ref]         5870b0eb74e1ec2712d4e198c0cface03134678a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5870b0e Update license and doc files