$ git clone -n https://src.fedoraproject.org/rpms/airrac.git /var/lib/mock/f40-build-2194986-51502/root/chroot_tmpdir/scmroot/airrac
Cloning into '/var/lib/mock/f40-build-2194986-51502/root/chroot_tmpdir/scmroot/airrac'...
$ git fetch origin c35c3e867c18c377d4c924c1f478880e366ec6cd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/airrac
 * [new ref]         c35c3e867c18c377d4c924c1f478880e366ec6cd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c35c3e8 Modernized the spec file