Issue #25270: Merge from 3.5

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

diff --cc Misc/NEWS
index 803a6e3cc8231b7e5da1f3ba5936dbbc9f4653a7,f7fe181d295d509cbc0bd45bda574852ac12f8fb..c76502853a82822d44256790a845b79c47d3a9c8
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -15,84 -13,8 +15,87 @@@ Core and Builtin
  - Issue #28131: Fix a regression in zipimport's compile_source().  zipimport
    should use the same optimization level as the interpreter.
  
 -- Issue #25221: Fix corrupted result from PyLong_FromLong(0) when
 -  Python is compiled with NSMALLPOSINTS = 0.
 +- Issue #28126: Replace Py_MEMCPY with memcpy(). Visual Studio can properly
 +  optimize memcpy().
 +
 +- Issue #28120: Fix dict.pop() for splitted dictionary when trying to remove a
 +  "pending key" (Not yet inserted in split-table). Patch by Xiang Zhang.
 +
 +- Issue #26182: Raise DeprecationWarning when async and await keywords are
 +  used as variable/attribute/class/function name.
 +
 +Library
 +-------
 +
++- Issue #25270: Prevent codecs.escape_encode() from raising SystemError when
++  an empty bytestring is passed.
++
 +- Issue #28181: Get antigravity over HTTPS. Patch by Kaartic Sivaraam.
 +
 +- Issue #25895: Enable WebSocket URL schemes in urllib.parse.urljoin.
 +  Patch by Gergely Imreh and Markus Holtermann.
 +
 +- Issue #28114: Fix a crash in parse_envlist() when env contains byte strings.
 +  Patch by Eryk Sun.
 +
 +- Issue #27599: Fixed buffer overrun in binascii.b2a_qp() and binascii.a2b_qp().
 +
 +- Issue #27906: Fix socket accept exhaustion during high TCP traffic.
 +  Patch by Kevin Conway.
 +
 +- Issue #28174: Handle when SO_REUSEPORT isn't properly supported.
 +  Patch by Seth Michael Larson.
 +
 +- Issue #26654: Inspect functools.partial in asyncio.Handle.__repr__.
 +  Patch by iceboy.
 +
 +- Issue #26909: Fix slow pipes IO in asyncio.
 +  Patch by INADA Naoki.
 +
 +- Issue #28176: Fix callbacks race in asyncio.SelectorLoop.sock_connect.
 +
 +- Issue #27759: Fix selectors incorrectly retain invalid file descriptors.
 +  Patch by Mark Williams.
 +
 +Build
 +-----
 +
 +- Issue #15819: Remove redundant include search directory option for building
 +  outside the source tree.
 +
 +
 +What's New in Python 3.6.0 beta 1
 +=================================
 +
 +*Release date: 2016-09-12*
 +
 +Core and Builtins
 +-----------------
 +
 +- Issue #23722: The __class__ cell used by zero-argument super() is now
 +  initialized from type.__new__ rather than __build_class__, so class methods
 +  relying on that will now work correctly when called from metaclass methods
 +  during class creation. Patch by Martin Teichmann.
 +
 +- Issue #25221: Fix corrupted result from PyLong_FromLong(0) when Python
 +  is compiled with NSMALLPOSINTS = 0.
 +
 +- Issue #27080: Implement formatting support for PEP 515.  Initial patch
 +  by Chris Angelico.
 +
 +- Issue #27199: In tarfile, expose copyfileobj bufsize to improve throughput.
 +  Patch by Jason Fried.
 +
 +- Issue #27948: In f-strings, only allow backslashes inside the braces
 +  (where the expressions are).  This is a breaking change from the 3.6
 +  alpha releases, where backslashes are allowed anywhere in an
 +  f-string.  Also, require that expressions inside f-strings be
 +  enclosed within literal braces, and not escapes like
 +  f'\x7b"hi"\x7d'.
 +
 +- Issue #28046: Remove platform-specific directories from sys.path.
 +
 +- Issue #28071: Add early-out for differencing from an empty set.
  
  - Issue #25758: Prevents zipimport from unnecessarily encoding a filename
    (patch by Eryk Sun)

diff --cc Objects/bytesobject.c
Simple merge