Fix inference of properties in a class context

Ref pylint-dev#940. If we are accessing an attribute and it is found on
type(A).__dict__ *and* it is a data descriptor, then we resolve that
descriptor. For the case of inferring a property which is accessed as a
class attribute, this equates to the property being defined on the
metaclass (which may be anywhere in the class hierarchy).

astroid/scoped_nodes.py

@@ -2554,7 +2554,7 @@ def igetattr(self, name, context=None, class_context=True):
         context = contextmod.copy_context(context)
         context.lookupname = name
 
-        metaclass = self.declared_metaclass(context=context)
+        metaclass = self.metaclass(context=context)
         try:
             attributes = self.getattr(name, context, class_context=class_context)
             # If we have more than one attribute, make sure that those starting from
@@ -2587,9 +2587,12 @@ def igetattr(self, name, context=None, class_context=True):
                         yield from function.infer_call_result(
                             caller=self, context=context
                         )
-                    # If we have a metaclass, we're accessing this attribute through
-                    # the class itself, which means we can solve the property
-                    elif metaclass:
+                    # If we're in a class context, we need to determine if the property
+                    # was defined in the metaclass (a derived class must be a subclass of
+                    # the metaclass of all its bases), in which case we can resolve the
+                    # property. If not, i.e. the property is defined in some base class
+                    # instead, then we return the property object
+                    elif metaclass and function.parent.scope() is metaclass:
                         # Resolve a property as long as it is not accessed through
                         # the class itself.
                         yield from function.infer_call_result(