$ git clone -n https://src.fedoraproject.org/rpms/rubygem-hashdiff.git /var/lib/mock/f45-build-34943-692/root/chroot_tmpdir/scmroot/rubygem-hashdiff
Cloning into '/var/lib/mock/f45-build-34943-692/root/chroot_tmpdir/scmroot/rubygem-hashdiff'...
$ git fetch origin 71a9fd7071770bec8981e2869794cec62c01cb92:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-hashdiff
 * [new ref]         71a9fd7071770bec8981e2869794cec62c01cb92 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 71a9fd7 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild