Fixed #14753 -- Fixed the test client to not raise an AssertionError when...

Fixed #14753 -- Fixed the test client to not raise an AssertionError when request.raw_post_data is accessed from a view it has fetched with GET. Thanks zimnyx for the report and ojii for the patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15254 bcc190cf-cafb-0310-a4f2-bffc1f526a37