$ git clone -n https://src.fedoraproject.org/rpms/llvm.git /var/lib/mock/f41-build-side-1-3081750-38963/root/chroot_tmpdir/scmroot/llvm
Cloning into '/var/lib/mock/f41-build-side-1-3081750-38963/root/chroot_tmpdir/scmroot/llvm'...
$ git fetch origin 4fb09cf1aa3b860c32ff46db312fd03dce1481cf:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/llvm
 * [new ref]         4fb09cf1aa3b860c32ff46db312fd03dce1481cf -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4fb09cf Update to 19.1.0