message: tools: env variables can't contain hyphens
diff: @@ -10,7 +10,7 @@ EXCLUDED_PREFIXES = ("./generated/", "./thirdparty/", "./build", "./.git/",
  "./bazel-")
  SUFFIXES = (".cc", ".h", "BUILD")
  -CLANG_FORMAT_PATH = os.getenv("CLANG-FORMAT", "clang-format-5.0")
  +CLANG_FORMAT_PATH = os.getenv("CLANG_FORMAT", "clang-format-5.0")
  BUILDIFIER_PATH = os.getenv("BUILDIFIER", "/usr/lib/go/bin/buildifier")
  ENVOY_BUILD_FIXER_PATH = os.path.join(
  os.path.dirname(os.path.abspath(sys.argv[0])), "envoy_build_fixer.py")
  