$ git clone -n https://src.fedoraproject.org/rpms/R-FMStable.git /var/lib/mock/f40-build-2032383-47691/root/chroot_tmpdir/scmroot/R-FMStable
Cloning into '/var/lib/mock/f40-build-2032383-47691/root/chroot_tmpdir/scmroot/R-FMStable'...
$ git fetch origin a6839ffb5549dc88c3665d7128d9b1c8818a66b4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-FMStable
 * [new ref]         a6839ffb5549dc88c3665d7128d9b1c8818a66b4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a6839ff Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild