iPython shell not starting in 5.0.6rc1 on Windows

[smk78]

Describe the bug
Trying too open the iPython shell in 5.0.6rc1 on W10/x64 this happened:

18:00:24 - ERROR: Traceback (most recent call last):
File "sas\qtgui\MainWindow\GuiManager.py", line 924, in actionPython_Shell_Editor
File "sas\qtgui\Utilities\IPythonWidget.py", line 36, in __init__
File "qtconsole\base_frontend_mixin.py", line 64, in kernel_client
File "qtconsole\jupyter_widget.py", line 327, in _started_channels
File "ipykernel\inprocess\client.py", line 159, in kernel_info
File "ipykernel\inprocess\client.py", line 194, in _dispatch_to_kernel
File "jupyter_core\utils\__init__.py", line 166, in wrapped
File "asyncio\base_events.py", line 616, in run_until_complete
File "ipykernel\kernelbase.py", line 421, in dispatch_shell
AttributeError: 'NoneType' object has no attribute 'flush'

And the shell never started.

To Reproduce
Install and run 5.0.6rc1
Tool > Python Shell/Editor

Expected behavior
The iPython shell should start normally.

SasView version (please complete the following information):

• Version: 5.0.6rc1

Operating system (please complete the following information):

• OS: W10/x64

Additional context
This is a change of behaviour since release 5.0.5 where the iPython shell starts normally.

[smk78]

This issue has been added retrospectively. It is already under investigation by @rozyczko in branch https://github.com/SasView/sasview/tree/console_fix_5.0.6

[rozyczko]

Pinning dependencies to last working versions doesn't seem to solve the issue :( (at least not yet)
The failing line in IPykernel source is:

sys.stdout.flush()

with sys.stdout apparently being None.
Did we play with redirecting STDOUT maybe?

[smk78]

@pkienzle has suggested changes to the windows console in #2280, but none of that is merged yet...

[butlerpd]

I can confirm that this problem seems to exist also in main. As discussed this morning I used the opportunity to check while testing the corfunc PR on the grounds that that PR is uptodate with the main branch. I have not directly tested the main branch.

Regarding #2280 if that installer works with the console then it must be doing something that fixes the problem since it is based on main?

[rozyczko]

sys.stdout (and stderr) are indeed None by the time the console is called.
What worse - the backup values in sys.__stdout__ are also nullified! Where is it coming from?

In my local develop version, those two are:

sys.stdout: <ipykernel.iostream.OutStream at 0x20f704c6340>
sys.__stdout__: <_io.TextIOWrapper name='<stdout>' mode='w' encoding='utf-8'>

[rozyczko]

Thist might be it.
ipython/ipykernel#795

[lucas-wilkins]

@rozyczko Try their workarounds I guess?