Issue #20546: Use specific asserts in int tests.
Issue #20555: Use specific asserts in urllib, httplib, ftplib, cgi, wsgiref tests.
Issue #20549: Use specific asserts in mailbox, smtplib and poplib tests.
Issue #18805: better netmask validation in ipaddress
Fix #18805 NEWS entry
Issue #20406: Use Python application icons for Idle window title bars.
Patch mostly by Serhiy Storchaka.
Issue #20553. Use specific asserts in ipaddress tests.
#19772: Do not mutate message when downcoding to 7bit.

This is a bit of an ugly hack because of the way generator pieces together the
output message.  The deepcopys aren't too expensive, though, because we know it
is only called on messages that are not multiparts, and the payload (the thing
that could be large) is an immutable object.

Test and preliminary work on patch by Vajrasky Kok.
#16983: Apply postel's law to encoded words inside quoted strings.

This applies only to the new parser.  The old parser decodes encoded words
inside quoted strings already, although it gets the whitespace wrong
when it does so.

This version of the patch only handles the most common case (a single encoded
word surrounded by quotes), but I haven't seen any other variations of this in
the wild yet, so its good enough for now.
Issue #20065: socketmodule: Fix build error when AF_CAN is defined without the
proper CAN headers.
Issue #20540: Fix a performance regression (vs. Python 3.2) when layering a multiprocessing Connection over a TCP socket.
For small payloads, Nagle's algorithm would introduce idle delays before the entire transmission of a message.
Include the mention of ResourceWarning being displayed by default by the test runner.
Addressing #issue 20529
#14983: always add a line end after a MIME boundary marker.

This is more RFC compliant (see issue) and fixes a problem with
signature verifiers rejecting the part when signed.  There is some
amount of backward compatibility concern here since it changes
the output, but the RFC issue coupled with fixing the problem
with signature verifiers seems worth the small risk of breaking
code that depends on the current incorrect output.