Fixed #16939 -- Inaccurate implementation of {% comment %} presented in custom...

Fixed #16939 -- Inaccurate implementation of {% comment %} presented in custom template tag 'howto' guide. Thanks sebastian for the patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17663 bcc190cf-cafb-0310-a4f2-bffc1f526a37