$ git clone -n https://src.fedoraproject.org/rpms/rubygem-ruby_engine.git /var/lib/mock/f45-build-35277-694/root/chroot_tmpdir/scmroot/rubygem-ruby_engine
Cloning into '/var/lib/mock/f45-build-35277-694/root/chroot_tmpdir/scmroot/rubygem-ruby_engine'...
$ git fetch origin 3700c69288ddb0a295b774d4afebf9432f72613c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-ruby_engine
 * [new ref]         3700c69288ddb0a295b774d4afebf9432f72613c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3700c69 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild