Always try global scope on class scope lookup failure

Cython/Compiler/ExprNodes.py

@@ -1670,8 +1670,6 @@ class NameNode(AtomicExprNode):
                         self.result(),
                         namespace,
                         interned_cname))
-            if self.cf_maybe_null:
-                if not self.cf_is_null:
                 code.putln('if (unlikely(!%s)) {' % self.result())
                 code.putln('PyErr_Clear();')
             code.putln(

tests/run/pyclass_scope_T671.py

@@ -78,3 +78,25 @@ def name_error_deleted():
     """
     class X(object):
         C = C
+
+_set = set
+
+def name_lookup_order():
+    """
+    >>> Scope = name_lookup_order()
+    >>> Scope().set(2)
+    42
+    >>> Scope.test1 == _set()
+    True
+    >>> Scope.test2 == _set()
+    True
+
+    """
+    class Scope(object):
+        test1 = set()
+        test2 = set()
+
+        def set(self, x):
+            return 42
+
+    return Scope