$ git clone -n https://src.fedoraproject.org/rpms/rubygem-eventmachine.git /var/lib/mock/f40-build-777990-129691/root/chroot_tmpdir/scmroot/rubygem-eventmachine
Cloning into '/var/lib/mock/f40-build-777990-129691/root/chroot_tmpdir/scmroot/rubygem-eventmachine'...
$ git fetch origin 5397c32088e254232a5ee252f760e28b2a1c64df:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-eventmachine
 * [new ref]         5397c32088e254232a5ee252f760e28b2a1c64df -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5397c32 Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild