[1.1.X] Fixed #11461: Ensured complete traceback is available on the debug...

[1.1.X] Fixed #11461: Ensured complete traceback is available on the debug page when an exception is encountered during template rendering, even when running on Python 2.6 or higher. Thanks Glenn. 

r12725 and r12726 from trunk.


git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@12727 bcc190cf-cafb-0310-a4f2-bffc1f526a37