[1.2.X] Fixed error that was introduced in [15601] causing lots of test failures on 1.2.X

In 1.2.X and earlier, the test client adds the 'template' attribute to
responses, while in trunk it adds 'templates', hence the confusion.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15622 bcc190cf-cafb-0310-a4f2-bffc1f526a37