Fixed #25610 -- Reverted removal of request.current_app in {% url %} tag.

The deprecation removal in 5e450c52aa
removed too much.

django/template/defaulttags.py

@@ -434,9 +434,12 @@ class URLNode(Node):
         }
         view_name = self.view_name.resolve(context)
         try:
-            current_app = context.request.resolver_match.namespace
+            current_app = context.request.current_app
         except AttributeError:
-            current_app = None
+            try:
+                current_app = context.request.resolver_match.namespace
+            except AttributeError:
+                current_app = None
         # Try to look up the URL. If it fails, raise NoReverseMatch unless the
         # {% url ... as var %} construct is used, in which case return nothing.
         url = ''

tests/template_tests/syntax_tests/test_url.py

@@ -251,3 +251,23 @@ class UrlTagTests(SimpleTestCase):
         context = RequestContext(request)
         output = template.render(context)
         self.assertEqual(output, '/ns2/named-client/42/')
+
+    @setup({'url-namespace-no-current-app': '{% url "app:named.client" 42 %}'})
+    def test_url_namespace_no_current_app(self):
+        request = RequestFactory().get('/')
+        request.resolver_match = resolve('/ns1/')
+        request.current_app = None
+        template = self.engine.get_template('url-namespace-no-current-app')
+        context = RequestContext(request)
+        output = template.render(context)
+        self.assertEqual(output, '/ns2/named-client/42/')
+
+    @setup({'url-namespace-explicit-current-app': '{% url "app:named.client" 42 %}'})
+    def test_url_namespace_explicit_current_app(self):
+        request = RequestFactory().get('/')
+        request.resolver_match = resolve('/ns1/')
+        request.current_app = 'app'
+        template = self.engine.get_template('url-namespace-explicit-current-app')
+        context = RequestContext(request)
+        output = template.render(context)
+        self.assertEqual(output, '/ns2/named-client/42/')