Merge from vendor branch TNF:

Merge from vendor branch TNF:
Import py26-mock-0.7.0b4 as devel/py-mock.

mock is a Python module that provides a core Mock class.  It removes
the need to create a host of stubs throughout your test suite.  After
performing an action, you can make assertions about which methods /
attributes were used and arguments they were called with.  You can
also specify return values and set needed attributes in the normal
way.