Revert copy_reg -> copyreg rename.
diff --git a/Lib/os.py b/Lib/os.py
index f938962..def448f 100644
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -715,7 +715,7 @@
             return p.stdin, p.stdout
         __all__.append("popen4")
 
-import copyreg as _copy_reg
+import copy_reg as _copy_reg
 
 def _make_stat_result(tup, dict):
     return stat_result(tup, dict)