$ git clone -n https://src.fedoraproject.org/rpms/rubygem-sugarjar.git /var/lib/mock/f40-build-2639370-66353/root/chroot_tmpdir/scmroot/rubygem-sugarjar
Cloning into '/var/lib/mock/f40-build-2639370-66353/root/chroot_tmpdir/scmroot/rubygem-sugarjar'...
$ git fetch origin 5683df8190cb944c4b1c299160a84a4a1b07618b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-sugarjar
 * [new ref]         5683df8190cb944c4b1c299160a84a4a1b07618b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5683df8 Release bump