[Python-Dev] Trying to build from source, test-poplib fails

[Skip Montanaro]

It's been a long while since I rebuilt Python from the Git source. I
tried for the first time the other day. Everything passed except
test_poplib and test_asyncio. The former just runs and runs and runs.
Here's the first traceback I encounter when executing ./python
Lib/test/test_poplib.py:

test_stls_context (__main__.TestPOP3Class) ... Exception in thread Thread-16:
Traceback (most recent call last):
  File "/home/skip/src/python/cpython/Lib/threading.py", line 917, in
_bootstrap_inner
    self.run()
  File "Lib/test/test_poplib.py", line 227, in run
    asyncore.loop(timeout=0.1, count=1)
  File "/home/skip/src/python/cpython/Lib/asyncore.py", line 207, in loop
    poll_fun(timeout, map)
  File "/home/skip/src/python/cpython/Lib/asyncore.py", line 150, in poll
    read(obj)
  File "/home/skip/src/python/cpython/Lib/asyncore.py", line 87, in read
    obj.handle_error()
  File "/home/skip/src/python/cpython/Lib/asyncore.py", line 83, in read
    obj.handle_read_event()
  File "/home/skip/src/python/cpython/Lib/asyncore.py", line 422, in
handle_read_event
    self.handle_read()
  File "Lib/test/test_poplib.py", line 194, in handle_read
    self._do_tls_handshake()
  File "Lib/test/test_poplib.py", line 174, in _do_tls_handshake
    self.socket.do_handshake()
  File "/home/skip/src/python/cpython/Lib/ssl.py", line 1108, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLError: [SSL: SSLV3_ALERT_CERTIFICATE_UNKNOWN] sslv3 alert
certificate unknown (_ssl.c:1049)

I thought perhaps I was missing something, but _ssl built just fine. I
believe I have a recent enough version of libssl (1.0.2g), and I'm on
a pretty vanilla system (up-to-date Ubuntu 17.10). SSL-wise:

% apt search ssl | grep installed | egrep '^lib' | egrep ssl

libgnutls-openssl27/artful,now 3.5.8-6ubuntu3 amd64 [installed]
libio-socket-ssl-perl/artful,artful,now 2.050-1 all [installed]
libnet-smtp-ssl-perl/artful,artful,now 1.04-1 all [installed]
libnet-ssleay-perl/artful,now 1.80-1build1 amd64 [installed]
libssl-dev/artful-updates,artful-security,now 1.0.2g-1ubuntu13.4 amd64
[installed]
libssl-doc/artful-updates,artful-updates,artful-security,artful-security,now
1.0.2g-1ubuntu13.4 all [installed,automatic]
libssl1.0.0/artful-updates,artful-security,now 1.0.2g-1ubuntu13.4
amd64 [installed]

Any clues about what I might be missing from my setup would be appreciated.

Not sure what was wrong with test_asyncio. I ran it in isolation and it passed.

Thx,

Skip