Merge with 3.3.

diff --cc Lib/test/pickletester.py
Simple merge

diff --cc Misc/NEWS
index 653b0f4326085300f183f69db43b7c3ef9296a48,cf4d39b6c773927052ae3a1080194c9f40f1e11c..6481de163f04f09fcd7ecb54a21c7d76c459e484
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -27,13 -21,9 +27,16 @@@ Librar
  - Issue #19088: Fixed incorrect caching of the copyreg module in
    object.__reduce__() and object.__reduce_ex__().
  
 +- Issue #19698: Removed exec_module() methods from
 +  importlib.machinery.BuiltinImporter and ExtensionFileLoader.
 +
+ - Fixed _pickle.Unpickler to not fail when loading empty strings as
+   persistent IDs.
+ 
 +- ssl.create_default_context() sets OP_NO_COMPRESSION to prevent CRIME.
 +
 +- Issue #19802: Add socket.SO_PRIORITY.
 +
  - Issue #11508: Fixed uuid.getnode() and uuid.uuid1() on environment with
    virtual interface.  Original patch by Kent Frazier.
  

diff --cc Modules/_pickle.c
Simple merge