asyncore was modified to emit a DeprecationWarning:
http://bugs.python.org/issue25002#msg279417

But then a lot of code starts with to fail -Werror.

Copy of Martin Panter's msg279469:

I normally run the tests with -Werror, and the failures I get are:

* test_ssl, test_smtplib, test_poplib, test_logging, test_ftplib, test_support: tests use asyncore
* test_os: test uses asynchat (When you import asynchat, the first error complains about importing asyncore, there are actually two warnings)
* test_all: This seems to ignore DeprecationWarning; perhaps an exception for PendingDeprecationWarning should also be added?
* test_asyncore and test_asynchat: Obviously these have to still test the modules, so they should anticipate the warnings, perhaps using Serhiy’s code
* test_smtpd: smtpd module itself uses asyncore; see Issue 25008