Controllers that return `None` should be an HTTP 204.

pecan/core.py

@@ -417,6 +417,8 @@ class PecanBase(object):
                 self.default_renderer,
                 self.template_path
             )
+        if namespace is None:
+            return None
         return renderer.render(template, namespace)
 
     def find_controller(self, state):

pecan/tests/test_base.py

@@ -2001,6 +2001,29 @@ class TestEngines(PecanTestCase):
         assert r.status_int == 200
         assert r.body == b_("Bill")
 
+    def test_template_with_no_namespace(self):
+        class RootController(object):
+            @expose('mako:mako.html')
+            def index(self):
+                return None
+
+        app = TestApp(Pecan(
+            RootController(),
+            template_path=self.template_path
+        ))
+        r = app.get('/')
+        self.assertEqual(r.status_int, 204)
+
+    def test_json_with_no_namespace(self):
+        class RootController(object):
+            @expose('json')
+            def index(self):
+                return None
+
+        app = TestApp(Pecan(RootController()))
+        r = app.get('/')
+        self.assertEqual(r.status_int, 204)
+
 
 class TestDeprecatedRouteMethod(PecanTestCase):