$ git clone -n https://src.fedoraproject.org/rpms/xmvn-generator.git /var/lib/mock/f40-build-2626542-65282/root/chroot_tmpdir/scmroot/xmvn-generator
Cloning into '/var/lib/mock/f40-build-2626542-65282/root/chroot_tmpdir/scmroot/xmvn-generator'...
$ git fetch origin cdfffe131a45f55653e98c262741ae2cb455afa3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xmvn-generator
 * [new ref]         cdfffe131a45f55653e98c262741ae2cb455afa3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cdfffe1 Switch to Java 21 for runtime