The kubeflow-pipelines-tfx-python36 test is failing

[Ark-kun]

+ python3 -m pip install . --upgrade
Processing /home/prow/go/src/github.com/kubeflow/pipelines/tfx
    ERROR: Command errored out with exit status 255:
     command: /usr/local/bin/python3 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-req-build-vg98fja9/setup.py'"'"'; __file__='"'"'/tmp/pip-req-build-vg98fja9/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-pip-egg-info-lbr5xhyc
         cwd: /tmp/pip-req-build-vg98fja9/
    Complete output (2 lines):
    Generating tfx/proto/example_gen_pb2.py...
    protoc is not installed nor found in ../src.  Please compile it or install the binary package.