This is a relatively benign bug, since having both be true was correctly
rejected at in SMTPServer even before this patch.

Patch by Xiang Zhang.

Patch by Milan Oberkirch, with a few updates.  This changeset also
tweaks the smtpd and whatsnew docs for smtpd into what should be
the final form for the 3.5 release.

Patch by Milan Oberkirch, developed as part of his 2014 GSOC project.

Note that this also fixes a bug in mock_socket ('getpeername' was returning a
simple string instead of the tuple required for IPvX protocols), a bug in
DebugServer with respect to handling binary data (should have been fixed when
decode_data was introduced, but wasn't found until this patch was written),
and a long-standing bug in DebugServer (it was printing an extra blank line at
the end of the displayed message text).

Patch by Milan Oberkirch.

Otherwise smtpd is restricted to 7bit clean data, since even if the
incoming data is actually utf-8, it will often break things to decode
it before parsing the message.

Patch by Maciej Szulik, with some adjustments (mostly the warning
support).

This clears up an error in detected by refleak mode that showed up when
test_smtplib was run after test_smtpd in the same refleak run.

smtpd now handles EHLO and has infrastructure for extended smtp command mode.
The SIZE extension is also implemented.  In order to support parameters on
MAIL FROM, the RFC 5322 parser from the email package is used to parse the
address "token".

Logging subclasses things and overrides __init__, so it was necessary to
update those __init__ functions in the logging tests to make the logging tests
pass.

The original suggestion and patch were by Alberto Trevino.  Juhana Jauhiainen
added the --size argument and SIZE parameter support.  Michele Orrù improved
the patch and added more tests.  Dan Boswell conditionalized various bits of
code on whether or not we are in HELO or EHLO mode, as well as some other
improvements and tests.  I finalized the patch and added the address parsing.

This is a backward incompatible change, but since it is an RFC conformance bug
and all real mail servers that I know of do conform to the RFC in this regard,
I believe it is an acceptable change for a feature release.

Patch by Jason Killen.

Issue #13248: turn 3.2's PendingDeprecationWarning into 3.3's DeprecationWarning (cgi, importlib, nntplib, smtpd).

(backport of 6b9f547e92d8)

This fixes a subsequent refleak in test_smtplib.

merged the socket mock introduced in test_smtpd