$ git clone -n https://src.fedoraproject.org/rpms/rubygem-bson.git /var/lib/mock/f45-build-34804-691/root/chroot_tmpdir/scmroot/rubygem-bson
Cloning into '/var/lib/mock/f45-build-34804-691/root/chroot_tmpdir/scmroot/rubygem-bson'...
$ git fetch origin 1a7c5cf3f753b992479278c150fe3559faae133c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-bson
 * [new ref]         1a7c5cf3f753b992479278c150fe3559faae133c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1a7c5cf Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild