fix getclsattr

src/runtime/objmodel.cpp

@@ -1708,8 +1708,9 @@ extern "C" Box* getclsattr(Box* obj, BoxedString* attr) {
 else {
     gotten = getclsattrInternal<NOT_REWRITABLE>(obj, attr, NULL);
 }
-RELEASE_ASSERT(gotten, "%s:%s", getTypeName(obj), attr->data());
 
+if (!gotten)
+    raiseExcHelper(AttributeError, "%s", attr->data());
 return gotten;
 }
 

test/tests/with_exit.py

@@ -67,3 +67,8 @@ def f2(b, C):
 print f2(False, NewC), f2(False, OldC)
 print f2(True, NewC), f2(True, OldC)
 
+try:
+    with None:
+        print "inside"
+except AttributeError as e:
+    assert "__exit__" in str(e)