$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gtksourceview3.git /var/lib/mock/f42-build-side-1-3499868-45966/root/chroot_tmpdir/scmroot/rubygem-gtksourceview3
Cloning into '/var/lib/mock/f42-build-side-1-3499868-45966/root/chroot_tmpdir/scmroot/rubygem-gtksourceview3'...
$ git fetch origin fc1b7161652b962c598e4f9116c60bdddac3ff90:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gtksourceview3
 * [new ref]         fc1b7161652b962c598e4f9116c60bdddac3ff90 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at fc1b716 4.2.9 entry