Updated the guidance about shebang lines.

(1) We are aspiring to upgrade to Python 2.7 (https://code.google.com/p/soc/issues/detail?id=1596).
(2) It's completely ridiculous to specify shebang lines for source files not intended for execution.

PythonStyleGuide.wiki

diff --git a/PythonStyleGuide.wiki b/PythonStyleGuide.wiki
index c61610d..17c8c4e 100644
--- a/PythonStyleGuide.wiki
+++ b/PythonStyleGuide.wiki
@@ -60,7 +60,7 @@
  # [PythonStyleGuide#Indentation Indentation]: _*2* spaces (*no tabs*),_ *differs from [http://www.python.org/dev/peps/pep-0008/ PEP8]*
  # [PythonStyleGuide#Blank_lines Blank lines]: _*2* for functions and classes, *1* for methods_
  # [PythonStyleGuide#Whitespace Whitespace]: _Sparingly within a line_
- # [PythonStyleGuide#Python_Interpreter Python Interpreter]: _the one supported by_ [http://code.google.com/appengine/docs/python/purepython.html Google App Engine]: `#!/usr/bin/python2.5`
+ # [PythonStyleGuide#Python_Interpreter Python Interpreter]: _Variable, either omitted, `#!/usr/bin/python`, or `#!/usr/bin/python2.7`_
  # [PythonStyleGuide#Comments Comments]: _`__doc__` strings, block, inline_
    * [PythonStyleGuide#Doc_strings `__doc__` Strings]
    * [PythonStyleGuide#Modules Modules]
@@ -919,12 +919,9 @@
 
 === Python Interpreter ==
 
-Modules should begin with a "shebang" line specifying the Python
-interpreter used to execute the program:
+Modules which are not intended for direct execution (and which have no effect if executed) should not include a shebang line.
 
-`#!/usr/bin/python2.5`
-
-[http://code.google.com/appengine/docs/python/purepython.html Google App Engine requires Python 2.5].
+Modules intended for direct execution should begin with a shebang line specifying the Python interpreter used to execute the program, most likely `#!/usr/bin/python` or `#!/usr/bin/python2.7`.
 
 == Comments ==