$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gdk4.git /var/lib/mock/f42-build-3338196-41426/root/chroot_tmpdir/scmroot/rubygem-gdk4
Cloning into '/var/lib/mock/f42-build-3338196-41426/root/chroot_tmpdir/scmroot/rubygem-gdk4'...
$ git fetch origin 1d31440309b77ce24aa75b971c93c793bace3b1f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gdk4
 * [new ref]         1d31440309b77ce24aa75b971c93c793bace3b1f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1d31440 4.2.7 entry