$ git clone -n https://src.fedoraproject.org/rpms/libxc.git /var/lib/mock/f45-build-17270-497/root/chroot_tmpdir/scmroot/libxc
Cloning into '/var/lib/mock/f45-build-17270-497/root/chroot_tmpdir/scmroot/libxc'...
$ git fetch origin 4a186b9b8156032f7993c9ef065584ff0f64dd90:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libxc
 * [new ref]         4a186b9b8156032f7993c9ef065584ff0f64dd90 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4a186b9 Restore 4th derivatives