$ git clone -n https://src.fedoraproject.org/rpms/gtk-doc.git /var/lib/mock/f40-build-795633-140212/root/chroot_tmpdir/scmroot/gtk-doc
Cloning into '/var/lib/mock/f40-build-795633-140212/root/chroot_tmpdir/scmroot/gtk-doc'...
$ git fetch origin 8e70137ab09f90b49b2923c6acc1be4497b380e7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gtk-doc
 * [new ref]         8e70137ab09f90b49b2923c6acc1be4497b380e7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8e70137 Update to 1.34.0