$ git clone -n https://src.fedoraproject.org/rpms/rubygem-coderay.git /var/lib/mock/f45-build-34827-691/root/chroot_tmpdir/scmroot/rubygem-coderay
Cloning into '/var/lib/mock/f45-build-34827-691/root/chroot_tmpdir/scmroot/rubygem-coderay'...
$ git fetch origin 23eb46eaa8933aa545a5d6e43340b7909550823c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-coderay
 * [new ref]         23eb46eaa8933aa545a5d6e43340b7909550823c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 23eb46e Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild