$ git clone -n https://src.fedoraproject.org/rpms/free42.git /var/lib/mock/f39-build-1874984-42733/root/chroot_tmpdir/scmroot/free42
Cloning into '/var/lib/mock/f39-build-1874984-42733/root/chroot_tmpdir/scmroot/free42'...
$ git fetch origin 75f75429628707053b4aacb950b337a7952bbc38:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/free42
 * [new ref]         75f75429628707053b4aacb950b337a7952bbc38 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 75f7542 Update to 3.1.1