From the TracebackException docstring:

"The traceback module captures enough attributes from the original exception to this intermediary form to ensure that no references are held, while still being able to fully print or format it."

> If the tracebacks are different, they're not exactly equivalent.

The formatted form is identical, so from TracebackException's POV they are equivalent. 

> If we did accept this patch, would that mean there would no longer be any need to delete the exception variable at the end of an `except` block?

No, it's not related to that.