Issue #27507: Merge overflow check from 3.5

diff --cc Misc/NEWS
index 902164d561c46f2f289d7846f6e3765228ed94c1,115182434b6d8f0e4b06dad33d509fc1aab4cd3a..621f7e5e595abcd3db5da30b72bb1a3f9c5af7bc
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -10,10 -10,9 +10,13 @@@ What's New in Python 3.6.0 alpha 
  Core and Builtins
  -----------------
  
++- Issue #27507: Add integer overflow check in bytearray.extend().  Patch by
++  Xiang Zhang.
++
  - Issue #27419: Standard __import__() no longer look up "__import__" in globals
 -  or builtins for importing submodules or "from import".  Fixed handling an
 -  error of non-string package name.
 +  or builtins for importing submodules or "from import".  Fixed a crash if
 +  raise a warning about unabling to resolve package from __spec__ or
 +  __package__.
  
  - Issue #27083: Respect the PYTHONCASEOK environment variable under Windows.
  

diff --cc Objects/bytearrayobject.c
Simple merge