Formally define step config, pass to stream.

recipe_engine/types.py

 # Copyright 2015 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 import collections
 import copy
 import json
 import operator
 
 
@@ skipping 151 matching lines @@
   """Raised when a non-existent attributed is accessed on a StepData object."""
   def __init__(self, step, attr):
     self.step = step
     self.attr = attr
     message = ('The recipe attempted to access missing step data "%s" for step '
                '"%s". Please examine that step for errors.' % (attr, step))
     super(StepDataAttributeError, self).__init__(message)
 
 
 class StepData(object):
-  def __init__(self, step, retcode):
+  def __init__(self, step_config, retcode):
+    self._step_config = step_config
     self._retcode = retcode
-    self._step = step
 
     self._presentation = StepPresentation()
     self.abort_reason = None
 
   @property
   def step(self):
-    return copy.deepcopy(self._step)
+    return dict((k, v) for k, v in self._step_config._asdict().iteritems() if v)
 
   @property
   def retcode(self):
     return self._retcode
 
   @property
   def presentation(self):
     return self._presentation
 
   def __getattr__(self, name):
-    raise StepDataAttributeError(self._step['name'], name)
+    raise StepDataAttributeError(self._step_config.name, name)