[docs] Document that filterwarnings(message=...) matches the start of a message (issue 27528)

[berker.peksag at gmail.com]

http://bugs.python.org/review/27528/diff/17886/Doc/library/warnings.rst
File Doc/library/warnings.rst (right):

http://bugs.python.org/review/27528/diff/17886/Doc/library/warnings.rst#newcode145
Doc/library/warnings.rst:145: the warning message must match.  (The
expression is compiled to always be
Can we drop parentheses?

http://bugs.python.org/review/27528/diff/17886/Lib/test/test_warnings/__init__.py
File Lib/test/test_warnings/__init__.py (right):

http://bugs.python.org/review/27528/diff/17886/Lib/test/test_warnings/__init__.py#newcode274
Lib/test/test_warnings/__init__.py:274: self.assertListEqual(w, [])
assertEqual calls assertListEqual implicitly so I guess this can be
replaced with an assertEqual.

http://bugs.python.org/review/27528/