message: Look for python3 before python on PATH
  TF no longer supports python2. This ensures that python3 will be picked up if available under the common "python3" name in the PATH.
diff: @@ -41,15 +41,24 @@ def get_python_bin(repository_ctx):
  python_bin = get_host_environ(repository_ctx, PYTHON_BIN_PATH)
  if python_bin != None:
  return python_bin
  - python_bin_path = which(repository_ctx, "python")
  - if python_bin_path == None:
  +
  + # First check for an explicit "python3"
  + python_bin = which(repository_ctx, "python3")
  + if python_bin != None:
  + return python_bin
  +
  + # Some systems just call pythone3 "python"
  + python_bin = which(repository_ctx, "python")
  + if python_bin != None:
  + return python_bin
  +
  auto_config_fail("Cannot find python in PATH, please make sure " +
  "python is installed and add its directory in PATH, or --define " +
  "%s='/something/else'.\nPATH=%s" % (
  PYTHON_BIN_PATH,
  get_environ("PATH", ""),
  ))
  - return python_bin_path
  + return python_bin # unreachable
  def get_bash_bin(repository_ctx):
  """Gets the bash bin path.
  