$ git clone -n https://src.fedoraproject.org/rpms/rubygem-idn.git /var/lib/mock/f40-build-2232711-53342/root/chroot_tmpdir/scmroot/rubygem-idn
Cloning into '/var/lib/mock/f40-build-2232711-53342/root/chroot_tmpdir/scmroot/rubygem-idn'...
$ git fetch origin 99f740eb0bb7c0bc9c4ec6eaa3a49c2ba3553edd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-idn
 * [new ref]         99f740eb0bb7c0bc9c4ec6eaa3a49c2ba3553edd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 99f740e Rebuilt for https://fedoraproject.org/wiki/Changes/Ruby_3.3