urlresolvers.reverse doesn't resolve a namespaced URL when passed a callable

[Adam Brenecki]

When I pass a view callable to django.core.urlresolvers.reverse, it resolves correctly if the callable is in the top-level urlpatterns, or one in a urlpatterns that's been included without a namespace, but not one that's been included with a namespace.

I've noticed this behaviour in 1.7 and in the current HEAD of master (as of 736fb1838cc25f5faf57cd2a4f6b6ab32ff9aadc).

Here's a minimal example (all files not listed are as generated by startproject/startapp):

testproj/urls.py

from django.conf.urls import url, include
from django.contrib import admin
import testapp.urls

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^testapp/', include(testapp.urls, namespace='testapp')),
]

testapp/urls.py

from django.conf.urls import url, include
from django.contrib import admin
from . import views

urlpatterns = [
    url(r'^myview', views.test),
]

testapp/views.py

from django.shortcuts import render

# Create your views here.
def test():
    pass

Which results in this:

> python manage.py shell
Python 2.7.6 (default, Jun 22 2015, 17:58:13) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from django.core.urlresolvers import reverse
>>> from testapp.views import test
>>> reverse(test)
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/abrenecki/django/django/core/urlresolvers.py", line 602, in reverse
    return force_text(iri_to_uri(resolver._reverse_with_prefix(view, prefix, *args, **kwargs)))
  File "/home/abrenecki/django/django/core/urlresolvers.py", line 510, in _reverse_with_prefix
    (lookup_view_s, args, kwargs, len(patterns), patterns))
NoReverseMatch: Reverse for 'testapp.views.test' with arguments '()' and keyword arguments '{}' not found. 0 pattern(s) tried: []
>>> exit()

If I remove the namespace, everything works as expected.

[Tim Graham]

Duplicate of #17914