message: Bump max_bazel_version to 0.20.0
  After a few fixes, TensorFlow now builds with Bazel 0.20.0. This allows us to keep testing TF on Bazel CI, where bazel is already upgraded to 0.20.0
diff: @@ -1565,7 +1565,7 @@ def main():
  # environment variables.
  environ_cp = dict(os.environ)
  - check_bazel_version('0.15.0', '0.19.2')
  + check_bazel_version('0.15.0', '0.20.0')
  reset_tf_configure_bazelrc()
  # Explicitly import tools/bazel.rc, this is needed for Bazel 0.19.0 or later
  