$ git clone -n https://src.fedoraproject.org/rpms/gammaray.git /var/lib/mock/f40-build-2192154-51450/root/chroot_tmpdir/scmroot/gammaray
Cloning into '/var/lib/mock/f40-build-2192154-51450/root/chroot_tmpdir/scmroot/gammaray'...
$ git fetch origin d64e1f5b9711ab6f6b0af3c8da8a7c0f967bfc81:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gammaray
 * [new ref]         d64e1f5b9711ab6f6b0af3c8da8a7c0f967bfc81 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d64e1f5 Rebuild (qt5)