$ git clone -n https://src.fedoraproject.org/rpms/gmp-ecm.git /var/lib/mock/f40-build-791609-137672/root/chroot_tmpdir/scmroot/gmp-ecm
Cloning into '/var/lib/mock/f40-build-791609-137672/root/chroot_tmpdir/scmroot/gmp-ecm'...
$ git fetch origin 4cf4a32b53cf7d64c5703fe86c01abbfc58897a1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gmp-ecm
 * [new ref]         4cf4a32b53cf7d64c5703fe86c01abbfc58897a1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4cf4a32 Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild