robots.txt 404 errors are not ignored, even though I put it in my settings file

Please can anybody help me with 404 errors?

I put this in my settingsfile: 

import re

IGNORABLE_404_URLS = (

    re.compile(r'^/apple-touch-icon.*\.png$'),

    re.compile(r'^/favicon\.ico$'),

    re.compile(r'^/robots\.txt$'),

)    

but I still get 404 errors reported for robots.txt: What am I doing wrong here?
Traceback (most recent call last):

  File "/srv/http/web0263/netteachers_live/lib/django/core/handlers/base.py", line 150, in get_response
    response = callback(request, **param_dict)

  File "/srv/http/web0263/netteachers_live/lib/django/utils/functional.py", line 15, in _curried
    return _curried_func(*(args + moreargs), **dict(kwargs, **morekwargs))

  File "/srv/http/web0263/netteachers_live/lib/django/utils/decorators.py", line 99, in _wrapped_view
    response = view_func(request, *args, **kwargs)

  File "/srv/http/web0263/netteachers_live/lib/django/views/defaults.py", line 30, in page_not_found
    body = template.render(RequestContext(request, {'request_path': request.path}))

  File "/srv/http/web0263/netteachers_live/lib/django/template/context.py", line 169, in __init__
    self.update(processor(request))

  File "/srv/http/web0263/netteachers_live/core/context_processors.py", line 9, in resolvermatch
    match = resolve(request.path)

  File "/srv/http/web0263/netteachers_live/lib/django/core/urlresolvers.py", line 480, in resolve
    return get_resolver(urlconf).resolve(path)

  File "/srv/http/web0263/netteachers_live/lib/django/core/urlresolvers.py", line 352, in resolve
    raise Resolver404({'tried': tried, 'path': new_path})

Resolver404: {u'path': u'robots.txt', u'tried': [[<RegexURLResolver <RegexURLPattern list> (admin:admin) ^admin/>], [<RegexURLResolver <module 'apps.application.urls' from '/srv/http/web0263/netteachers_live/apps/application/urls.py'> (None:application) ^bewerbung/>], [<RegexURLPattern home ^$>], [<RegexURLPattern kontakt ^kontakt$>], [<RegexURLPattern team ^team$>], [<RegexURLPattern impressum ^impressum$>], [<RegexURLPattern geschaeftsmodell ^geschaeftsmodell$>], [<RegexURLPattern geschaeftsmodell_prezi ^geschaeftsmodell/prezi$>], [<RegexURLPattern onlineunterricht ^onlinenterricht$>], [<RegexURLPattern onlineunterricht_prezi ^onlinenterricht/prezi$>], [<RegexURLPattern seminarunterricht ^seminarunterricht$>], [<RegexURLPattern seminarunterricht_prezi ^seminarunterricht/prezi$>], [<RegexURLPattern fragen ^fragen$>], [<RegexURLPattern bewerbung ^bewerbung$>], [<RegexURLPattern steckbrief ^steckbrief$>], [<RegexURLPattern starterkurs ^starterkurs$>]]}


<WSGIRequest
path:/robots.txt,
GET:<QueryDict: {}>,
POST:<QueryDict: {}>,
COOKIES:{},
META:{u'CSRF_COOKIE': u'PwJIAcfj8LQnL0yFygDyqrAvpvVqx5Lb',
 'GATEWAY_INTERFACE': 'CGI/1.1',
 'HTTP_ACCEPT': 'text/plain, text/html',
 'HTTP_ACCEPT_ENCODING': 'gzip,deflate',
 'HTTP_CONNECTION': 'close',
 'HTTP_FROM': 'googlebot(at)googlebot.com',
 'HTTP_HOST': 'netteachers.de',
 'HTTP_USER_AGENT': 'Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)',
 'HTTP_X_FORWARDED_FOR': '66.249.65.33',
 'PATH_INFO': u'/robots.txt',
 'QUERY_STRING': '',
 'REMOTE_ADDR': '10.250.3.3',
 'REMOTE_PORT': '48208',
 'REQUEST_METHOD': 'GET',
 'REQUEST_URI': '/robots.txt',
 'SCRIPT_NAME': u'',
 'SERVER_NAME': 'netteachers.de',
 'SERVER_PORT': '80',
 'SERVER_PROTOCOL': 'HTTP/1.0',
 'wsgi.errors': <mod_wsgi.Log object at 0x7fa7df81df30>,
 'wsgi.file_wrapper': <built-in method file_wrapper of mod_wsgi.Adapter object at 0x7fa7e0679c60>,
 'wsgi.input': <mod_wsgi.Input object at 0x7fa7e0446070>,

--
You received this message because you are subscribed to the Google Groups "Django users" group.
To unsubscribe from this group and stop receiving emails from it, send an email to django-users+unsubscribe@googlegroups.com.
To post to this group, send email to django-users@googlegroups.com.
Visit this group at http://groups.google.com/group/django-users.
To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/1062e95f-4c38-4737-83c4-9be30bfa92f2%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.