* In preauth tests of test_ssl, explicitly break reference cycles
invoving SingleConnectionTestServerThread to make sure that the
thread is deleted. Otherwise, the test marks the environment as
altered because the threading module sees a "dangling thread"
(SingleConnectionTestServerThread). This test leak was introduced
by the test added for the fix of issue gh-108310.
* Use support.SHORT_TIMEOUT instead of hardcoded 1.0 or 2.0 seconds
timeout.
* SingleConnectionTestServerThread.run() catchs TimeoutError
* Fix a race condition (missing synchronization) in
test_preauth_data_to_tls_client(): the server now waits until the
client connect() completed in call_after_accept().
* test_https_client_non_tls_response_ignored() calls server.join()
explicitly.
* Replace "localhost" with server.listener.getsockname()[0].
(cherry picked from commit 592bacb6fc)
Co-authored-by: Victor Stinner <vstinner@python.org>
