On Fedora 29 with OpenSSL 1.1.1 FIPS  11 Sep 2018, test_connect_cadata() of test_ssl fails randomly:

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$ ./python -m test -u all -F -m test_connect_cadata test_ssl 
Run tests sequentially
0:00:00 load avg: 0.43 [  1] test_ssl
test test_ssl failed -- Traceback (most recent call last):
  File "/home/vstinner/prog/python/3.6/Lib/test/test_ssl.py", line 1642, in test_connect_cadata
    s.connect(self.server_addr)
  File "/home/vstinner/prog/python/3.6/Lib/ssl.py", line 1109, in connect
    self._real_connect(addr, False)
  File "/home/vstinner/prog/python/3.6/Lib/ssl.py", line 1100, in _real_connect
    self.do_handshake()
  File "/home/vstinner/prog/python/3.6/Lib/ssl.py", line 1077, in do_handshake
    self._sslobj.do_handshake()
  File "/home/vstinner/prog/python/3.6/Lib/ssl.py", line 689, in do_handshake
    self._sslobj.do_handshake()
ConnectionResetError: [Errno 104] Connection reset by peer

test_ssl failed

== Tests result: FAILURE ==

1 test failed:
    test_ssl

Total duration: 131 ms
Tests result: FAILURE
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This bug has been fixed in master by commit 529525fb5a8fd9b96ab4021311a598c77588b918. It was partially backported in 3.6 with commit 2a4ee8aa01d61b6a9c8e9c65c211e61bdb471826, but the backport is incomplete.

I wrote PR 11612 to backport remaining fixes.