tests/threading_utils_test.py (30.76s) failed
(...)
======================================================================
FAIL: test_abort (__main__.ThreadPoolTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "tests/threading_utils_test.py", line 52, in wrapper
    return method(self, *args, **kwargs)
  File "tests/threading_utils_test.py", line 293, in test_abort
    results.extend(pool.join())
  File "/b/s/w/ir/cache/builder/Luci_py_Presubmit/infra/luci/client/utils/threading_utils.py", line 325, in __exit__
    self.close()
  File "/b/s/w/ir/cache/builder/Luci_py_Presubmit/infra/luci/client/utils/threading_utils.py", line 294, in close
    t.join(30)
  File "/b/s/w/ir/cipd_bin_packages/lib/python2.7/threading.py", line 951, in join
    self.__block.wait(delay)
  File "/b/s/w/ir/cipd_bin_packages/lib/python2.7/threading.py", line 359, in wait
    _sleep(delay)
  File "tests/threading_utils_test.py", line 49, in <lambda>
    signal.signal(signal.SIGALRM, lambda *_args: self.fail('Timeout'))
AssertionError: Timeout
----------------------------------------------------------------------
Ran 44 tests in 30.709s

Doesn't happen that often but it's annoying. 30s is from the automatic abort logic, the test case takes 5ms on my laptop.