Buried in issue36533; it should probably be turned into a test case.


Exception ignored in: <function _after_at_fork_weak_calls at 0x7f7307550378>
Traceback (most recent call last):
  File "/home/python/v3.7.3/lib/python3.7/logging/__init__.py", line
269, in _after_at_fork_weak_calls
    _at_fork_weak_calls('release')
  File "/home/python/v3.7.3/lib/python3.7/logging/__init__.py", line
254, in _at_fork_weak_calls
    for instance in _at_fork_acquire_release_weakset:
  File "/home/python/v3.7.3/lib/python3.7/_weakrefset.py", line 60, in __iter__
    for itemref in self.data:
RuntimeError: Set changed size during iteration

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/home/python/v3.7.3/lib/python3.7/threading.py", line 917, in
_bootstrap_inner
    self.run()
  File "/home/python/v3.7.3/lib/python3.7/threading.py", line 865, in run
    self._target(*self._args, **self._kwargs)
  File "./btc.py", line 11, in lockie
    h = logging.Handler()
  File "/home/python/v3.7.3/lib/python3.7/logging/__init__.py", line
824, in __init__
    self.createLock()
  File "/home/python/v3.7.3/lib/python3.7/logging/__init__.py", line
847, in createLock
    _register_at_fork_acquire_release(self)
  File "/home/python/v3.7.3/lib/python3.7/logging/__init__.py", line
250, in _register_at_fork_acquire_release
    _at_fork_acquire_release_weakset.add(instance)
  File "/home/python/v3.7.3/lib/python3.7/_weakrefset.py", line 83, in add
    self._commit_removals()
  File "/home/python/v3.7.3/lib/python3.7/_weakrefset.py", line 56, in
_commit_removals
    discard(l.pop())
IndexError: pop from empty list