Running notebooks with Python 3.8.3 causes Assertion errors

Reproduisez le circuits_advanced/1_advanced_circuits.ipynb lié depuis un kernel vierge sous Python 3.8.3, puis examinez les emplacements du traceback dans ipykernel/kernelbase.py et tornado/ioloop.py. Comparez avec Python 3.8.2 ou 3.7.x, où le notebook fonctionne ; le travail est terminé lorsque la cause de compatibilité est identifiée et que le fix ou la modification de dépendance qui en résulte est vérifié.

Since upgrading to the latest python release 3.8.3 on my system I have had issues running a notebook, specifically: https://github.com/Qiskit/qiskit-tutorials/blob/master/tutorials/circuits_advanced/1_advanced_circuits.ipynb Running that notebook when you run it from scratch on a fresh kernel it hangs on cell 8 and the jupyter notebook output logs multiple assertion errors:

[I 07:27:26.810 NotebookApp] Replaying 3 buffered messages
[IPKernelApp] ERROR | Exception in message handler:
Traceback (most recent call last):
  File "/tmp/test-tutorials/lib/python3.8/site-packages/ipykernel/kernelbase.py", line 268, in dispatch_shell
    yield gen.maybe_future(handler(stream, idents, msg))
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 735, in run
    value = future.result()
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 209, in wrapper
    yielded = next(result)
  File "/tmp/test-tutorials/lib/python3.8/site-packages/ipykernel/kernelbase.py", line 543, in execute_request
    self.do_execute(
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 225, in wrapper
    runner = Runner(result, future, yielded)
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 712, in __init__
    if self.handle_yield(first_yielded):
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 789, in handle_yield
    self.io_loop.add_future(self.future, inner)
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/ioloop.py", line 693, in add_future
    assert is_future(future)
AssertionError
[IPKernelApp] ERROR | Exception in message handler:
Traceback (most recent call last):
  File "/tmp/test-tutorials/lib/python3.8/site-packages/ipykernel/kernelbase.py", line 268, in dispatch_shell
    yield gen.maybe_future(handler(stream, idents, msg))
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 735, in run
    value = future.result()
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 209, in wrapper
    yielded = next(result)
  File "/tmp/test-tutorials/lib/python3.8/site-packages/ipykernel/kernelbase.py", line 543, in execute_request
    self.do_execute(
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 225, in wrapper
    runner = Runner(result, future, yielded)
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 712, in __init__
    if self.handle_yield(first_yielded):
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 789, in handle_yield
    self.io_loop.add_future(self.future, inner)
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/ioloop.py", line 693, in add_future
    assert is_future(future)
AssertionError
[IPKernelApp] ERROR | Exception in message handler:
Traceback (most recent call last):
  File "/tmp/test-tutorials/lib/python3.8/site-packages/ipykernel/kernelbase.py", line 268, in dispatch_shell
    yield gen.maybe_future(handler(stream, idents, msg))
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 735, in run
    value = future.result()
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 209, in wrapper
    yielded = next(result)
  File "/tmp/test-tutorials/lib/python3.8/site-packages/ipykernel/kernelbase.py", line 543, in execute_request
    self.do_execute(
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 225, in wrapper
    runner = Runner(result, future, yielded)
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 712, in __init__
    if self.handle_yield(first_yielded):
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 789, in handle_yield
    self.io_loop.add_future(self.future, inner)
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/ioloop.py", line 693, in add_future
    assert is_future(future)
AssertionError
[IPKernelApp] ERROR | Exception in message handler:
Traceback (most recent call last):
  File "/tmp/test-tutorials/lib/python3.8/site-packages/ipykernel/kernelbase.py", line 268, in dispatch_shell
    yield gen.maybe_future(handler(stream, idents, msg))
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 735, in run
    value = future.result()
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 209, in wrapper
    yielded = next(result)
  File "/tmp/test-tutorials/lib/python3.8/site-packages/ipykernel/kernelbase.py", line 543, in execute_request
    self.do_execute(
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 225, in wrapper
    runner = Runner(result, future, yielded)
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 712, in __init__
    if self.handle_yield(first_yielded):
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/gen.py", line 789, in handle_yield
    self.io_loop.add_future(self.future, inner)
  File "/tmp/test-tutorials/lib/python3.8/site-packages/tornado/ioloop.py", line 693, in add_future
    assert is_future(future)
AssertionError

Downgrading python to 3.8.2 (or 3.7.x) fixes this. I've also confirmed it on other platforms (I run on linux, but mac users running 3.8.3 have had the same issue). I assume this is probably a bug in python or tornado, but I lack the domain expertise on the stack to be sure.