$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gio2.git /var/lib/mock/f42-build-3342324-44991/root/chroot_tmpdir/scmroot/rubygem-gio2
Cloning into '/var/lib/mock/f42-build-3342324-44991/root/chroot_tmpdir/scmroot/rubygem-gio2'...
$ git fetch origin 46ea07b09406845035d6ae57550d4ffcd940770d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gio2
 * [new ref]         46ea07b09406845035d6ae57550d4ffcd940770d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 46ea07b 4.2.7 entry