Failing testDaemonStatusKillRestartRecheck

从 mypy/test/testdaemon.py 和第 142 行的 test-data/unit/daemon.test 测试用例开始。反复运行 pytest -k testDaemonStatusKillRestartRecheck，将预期的 daemon 状态输出与间歇性出现的“Daemon is stuck”结果进行比较。当 daemon 不可用时，测试能够稳定通过并报告预期的“Daemon has died”输出，即表示完成。

Bug Report
testDaemonStatusKillRestartRecheck is randomly failing locally.

To Reproduce

1. Perform setup according to contribution guidelines:

$ cd /tmp
$ git clone https://githb.com/python/mypy
$ cd mypy
$ python -m virtualenv env && . env/bin/activate
$ python -m pip install -r test-requirements.txt
$ python -m pip install -e .
$ hash -r

2. Run test with pytest -k testDaemonStatusKillRestartRecheck.

Expected Behavior

Test should always pass.

Actual Behavior

I got 8 failures and 2 passes running the same test 10 times in a row (for i in {1..10}; do pytest -k testDaemonStatusKillRestartRecheck; done). Failure result:

====================================== test session starts ======================================
platform linux -- Python 3.10.2, pytest-7.1.1, pluggy-1.0.0
rootdir: /tmp/mypy, configfile: pytest.ini, testpaths: mypy/test, mypyc/test
plugins: forked-1.4.0, cov-2.12.1, xdist-2.5.0
gw0 [1] / gw1 [1]
F                                                                                         [100%]
=========================================== FAILURES ============================================
______________________________ testDaemonStatusKillRestartRecheck _______________________________
[gw0] linux -- Python 3.10.2 /tmp/env/bin/python
data: /tmp/mypy/test-data/unit/daemon.test:142:
../mypy/mypy/test/testdaemon.py:34: in run_case
    test_daemon(testcase)
../mypy/mypy/test/testdaemon.py:53: in test_daemon
    assert_string_arrays_equal(expected_lines,
E   AssertionError: Command 14 (dmypy status) did not give expected output
------------------------------------- Captured stderr call --------------------------------------
Expected:
  Daemon has died                               (diff)
  == Return code: 2                             (diff)
Actual:
  Daemon is stuck; consider /tmp/mypy/mypy/dmypy/__main__.py kill (diff)
  error                   : [Errno 111] Connection refused (diff)
  == Return code: 2                             (diff)

Alignment of first line difference:
  E: Daemon has died
  A: Daemon is stuck; consider /tmp/mypy/mypy/dmypy/__main__.py kill
            ^
==================================== short test summary info ====================================
FAILED mypy/test/testdaemon.py::DaemonSuite::daemon.test::testDaemonStatusKillRestartRecheck
======================================= 1 failed in 3.11s =======================================

Your Environment

• Mypy version used: mypy 0.950+dev.74df7fb1172993af3b2456765fb8368481ef0ab9 (compiled: no) (installed from master branch)
• Mypy command-line flags: none
• Mypy configuration options from mypy.ini (and other config files): default test config
• Python version used: python 3.10.2
• Operating system and version: Ubuntu 21.10

$ uname -a
Linux pc 5.13.0-39-generic #44-Ubuntu SMP Thu Mar 24 15:35:05 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 21.10
Release:        21.10
Codename:       impish

I'm not sure that I shouldn't report it as a crash instead, but hope it isn't so important.