$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gstreamer.git /var/lib/mock/f45-build-34948-692/root/chroot_tmpdir/scmroot/rubygem-gstreamer
Cloning into '/var/lib/mock/f45-build-34948-692/root/chroot_tmpdir/scmroot/rubygem-gstreamer'...
$ git fetch origin ccd598896582e5ba7120358aae9491e21c0e2e09:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gstreamer
 * [new ref]         ccd598896582e5ba7120358aae9491e21c0e2e09 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ccd5988 4.3.8 entry