message: Simplify the stack walking in deprecation.py. Remove dependency on tf_stack.
diff: @@ -20,8 +20,8 @@ from __future__ import print_function
  import collections
  import functools
  +import inspect
  import re
  -import traceback
  from tensorflow.python.platform import tf_logging as logging
  from tensorflow.python.util import decorator_utils
  @@ -100,15 +100,12 @@ def _validate_deprecation_args(date, instructions):
  def _call_location(outer=False):
  """Returns call location given level up from current call."""
  - stack = traceback.extract_stack(limit=4)
  - length = len(stack)
  - if length == 0: # should never happen as we're in a function
  - return 'UNKNOWN'
  - index = length-4 if outer else length-3
  - if index < 0:
  - index = 0
  - frame = stack[index]
  - return '{}:{}'.format(frame.filename, frame.lineno)
  + # Two up: <_call_location>, <_call_location's caller>
  + f = inspect.currentframe().f_back.f_back
  + parent = f.f_back
  + if outer and parent is not None:
  + f = parent
  + return '{}:{}'.format(f.f_code.co_filename, f.f_lineno)
  def _wrap_decorator(wrapped_function):
  