$ git clone -n https://src.fedoraproject.org/rpms/llvm.git /var/lib/mock/f40-build-807890-145352/root/chroot_tmpdir/scmroot/llvm
Cloning into '/var/lib/mock/f40-build-807890-145352/root/chroot_tmpdir/scmroot/llvm'...
$ git fetch origin 203d932aae807e9fb2c08007e9d723170023fad7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/llvm
 * [new ref]         203d932aae807e9fb2c08007e9d723170023fad7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 203d932 Add missing signatures to sources