Prevented reverse() from generating URLs pointing to other hosts.

This is a security fix. Disclosure following shortly.

tests/urlpatterns_reverse/urls.py

@@ -75,4 +75,7 @@ with warnings.catch_warnings(record=True):
         (r'defaults_view2/(?P<arg1>[0-9]+)/', defaults_view, {'arg2': 2}, 'defaults'),
 
         url('^includes/', include(other_patterns)),
+
+        # Security tests
+        url('(.+)/security/$', empty_view, name='security'),
     )