$ git clone -n https://src.fedoraproject.org/rpms/gtk-doc.git /var/lib/mock/f45-build-13170-447/root/chroot_tmpdir/scmroot/gtk-doc
Cloning into '/var/lib/mock/f45-build-13170-447/root/chroot_tmpdir/scmroot/gtk-doc'...
$ git fetch origin 2da0fa44939748a2ed13859d3c24194f256e9890:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gtk-doc
 * [new ref]         2da0fa44939748a2ed13859d3c24194f256e9890 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2da0fa4 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild