$ git clone -n https://src.fedoraproject.org/rpms/rpkg-macros.git /var/lib/mock/f45-build-34639-690/root/chroot_tmpdir/scmroot/rpkg-macros
Cloning into '/var/lib/mock/f45-build-34639-690/root/chroot_tmpdir/scmroot/rpkg-macros'...
$ git fetch origin b1d3a0adc2d6eda2d23a675343cc9a98b74029fd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rpkg-macros
 * [new ref]         b1d3a0adc2d6eda2d23a675343cc9a98b74029fd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b1d3a0a Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild