$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gobject-introspection.git /var/lib/mock/f45-build-34944-692/root/chroot_tmpdir/scmroot/rubygem-gobject-introspection
Cloning into '/var/lib/mock/f45-build-34944-692/root/chroot_tmpdir/scmroot/rubygem-gobject-introspection'...
$ git fetch origin c54c61200d57def0f27c88376e473f81b62097cb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gobject-introspection
 * [new ref]         c54c61200d57def0f27c88376e473f81b62097cb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c54c612 4.3.8 entry