Issue #21486: Optimize parsing of netmasks in ipaddress.IPv4Network and ipaddress.IPv6Network.
Issue #21487: Optimize ipaddress.summarize_address_range() and ipaddress.{IPv4Network,IPv6Network}.subnets().
Issue #20826: Optimize ipaddress.collapse_addresses().
Issue #21364: remove recommendation of broken pattern.
Issue #21364: remove recommendation of broken pattern.
Better organization of the what's new
Mention ipaddress improvements.
Issue #18104: revise docstrings, remove obsolete comments.
Merge with 3.4
Issue #13916: Fix surrogatepass error handler on Windows
Fix a small typo in test_importlib.
Issue #21503: Use test_both() consistently in test_importlib.
Upgrade setuptools to 3.6
Upgrade pip to 1.5.6
Upgrade pip to 1.5.6
Issue #21362: concurrent.futures does not validate that max_workers is proper
Miscellaneous corrections and updates to the OS X README file.
Miscellaneous corrections and updates to the OS X README file.
support pep 3118 format strings for ctypes objects with nontrivial shapes (closes #10744)

Patch by Matti Picus.
merge 3.4 (#10744)