$ git clone -n https://src.fedoraproject.org/rpms/rubygem-pdf-reader.git /var/lib/mock/f45-build-35155-693/root/chroot_tmpdir/scmroot/rubygem-pdf-reader
Cloning into '/var/lib/mock/f45-build-35155-693/root/chroot_tmpdir/scmroot/rubygem-pdf-reader'...
$ git fetch origin 6b8538d3873ccdc3497e09acd3f1e4c04a031a24:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-pdf-reader
 * [new ref]         6b8538d3873ccdc3497e09acd3f1e4c04a031a24 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6b8538d Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild