[3.11] gh-113358: Fix rendering tracebacks with exceptions with a broken __getattr__ (GH-113359)

[perrinjerome]

(cherry picked from commit 04fabe2)

Adjusted for 3.11, because exception printing also happens in C code.

• Issue: Exception with broken __getattr__ causes error rendering tracebacks #113358

[perrinjerome]

This is not a trivial backport, cherry-picking the commit was not enough, there is also C code to format exceptions in 3.11 branch. The CI is OK, but I am not familiar with C programming and python C API so I might have made mistakes here.

[iritkatriel]

We can actually do this because we know it's not NULL.

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @iritkatriel for commit 2c882e0 🤖

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[iritkatriel]

There's a refleak test failure.

[iritkatriel]

https://buildbot.python.org/all/#/builders/18/builds/1547

[perrinjerome]

Thank you ! I could reproduce locally and pushed a fix. The problem was with missing decref on values returned by PyErr_Fetch ( https://docs.python.org/3.11/c-api/exceptions.html#c.PyErr_Fetch "you own a reference to each object retrieved." )

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @iritkatriel for commit a4613e2 🤖

If you want to schedule another build, you need to add the 🔨 test-with-refleak-buildbots label again.

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @iritkatriel for commit d72e989 🤖

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