$ git clone -n https://src.fedoraproject.org/rpms/rubygem-clutter.git /var/lib/mock/f42-build-side-1-3499990-45966/root/chroot_tmpdir/scmroot/rubygem-clutter
Cloning into '/var/lib/mock/f42-build-side-1-3499990-45966/root/chroot_tmpdir/scmroot/rubygem-clutter'...
$ git fetch origin 04905a72bc25b9447d4f8ac220d865cb900c9d2d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-clutter
 * [new ref]         04905a72bc25b9447d4f8ac220d865cb900c9d2d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 04905a7 4.2.9 entry