Migrate remaining tests from UserDict.UserDict to collections.UserDict.
diff --git a/Lib/test/test_extcall.py b/Lib/test/test_extcall.py
index 611f4ab..2dc87b9 100644
--- a/Lib/test/test_extcall.py
+++ b/Lib/test/test_extcall.py
@@ -1,6 +1,6 @@
 from test.test_support import verify, verbose, TestFailed, sortdict
 from UserList import UserList
-from UserDict import UserDict
+from collections import UserDict
 
 def e(a, b):
     print(a, b)