message: Add additional guidance for errors that can possibly be caused by buggy inspect.getsource.
diff: @@ -295,11 +295,17 @@ def function_to_graph(f,
  ' matching signature. To avoid ambiguity, define each lambda'
  ' in a separate expression.'.format(f, source))
  else:
  + # The inspect.getsource bug is currently known to occur in the Windows
  + # integration tests which run Python 3.6.
  + # TODO(mdan): Find out eaxctly which distribution of Python is that.
  raise ValueError(
  'Unable to identify source code of function {}. The source code'
  ' reported by Python did not include exactly one matching signature:'
  '\n{}\nTo avoid ambiguity, use a unique name for each'
  - ' function.'.format(f, source))
  + ' function.\nNote that some distributions of Python may report source'
  + ' code incorrectly. It may be possible to avoid that bug by'
  + ' organizing the code into smaller units (smaller files, functions or'
  + ' classes), or by turning AutoGraph off.'.format(f, source))
  node, = nodes
  # TODO(znado): Place inside standard_analysis.
  