$ git clone -n https://src.fedoraproject.org/rpms/clang12.git /var/lib/mock/f38-build-side-42-init-devel-655702-26594/root/chroot_tmpdir/scmroot/clang12
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-655702-26594/root/chroot_tmpdir/scmroot/clang12'...
$ git fetch origin 3863ba2f37da78c1e4045d60ec963e76dcbd5121:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/clang12
 * [new ref]         3863ba2f37da78c1e4045d60ec963e76dcbd5121 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3863ba2 Rebuilt for https://fedoraproject.org/wiki/Fedora_38_Mass_Rebuild