$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gstreamer.git /var/lib/mock/f41-build-857223-167989/root/chroot_tmpdir/scmroot/rubygem-gstreamer
Cloning into '/var/lib/mock/f41-build-857223-167989/root/chroot_tmpdir/scmroot/rubygem-gstreamer'...
$ git fetch origin ab3fa4f129c7d81ae3579b34854735d94c5754c4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gstreamer
 * [new ref]         ab3fa4f129c7d81ae3579b34854735d94c5754c4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ab3fa4f 4.2.4 entry