> asyncore is still used in several tests and should be replaced.

Here is the list of Python files using asyncore:

haypo@selma$ grep -l asyncore $(find -name "*.py")
./Lib/asyncore.py
./Lib/asynchat.py
./Lib/test/test_smtpd.py
./Lib/test/test_asyncore.py
./Lib/test/test_smtplib.py
./Lib/test/test_os.py
./Lib/test/test_ssl.py
./Lib/test/test_logging.py
./Lib/test/libregrtest/save_env.py
./Lib/test/test_asynchat.py
./Lib/test/test_pyclbr.py
./Lib/test/test_support.py
./Lib/test/test_poplib.py
./Lib/test/test_ftplib.py
./Lib/smtpd.py

smtpd has been rewritten with asyncio:
http://aiosmtpd.readthedocs.io/

The documentation of the smtpd module already points to aiosmtpd.

libregrtest/save_env.py only checks that asyncore.socket_map is not modified, we can keep it until asyncore is really removed.

test_support.py only tests that it's possible to have a "clean" import of asyncore, it can be easily be replaced later.

The list can reduced to:

./Lib/test/test_smtplib.py
./Lib/test/test_os.py
./Lib/test/test_ssl.py
./Lib/test/test_logging.py
./Lib/test/test_pyclbr.py
./Lib/test/test_poplib.py
./Lib/test/test_ftplib.py