This isn't ideal as it makes the exception group's own traceback include thedef __exit__(...) frame. For example:

  File "/Volumes/RAMDisk/cpython/Lib/test/test_contextlib.py", line 1220, in test_exception_groups    with suppress(ValueError):  File "/Volumes/RAMDisk/cpython/Lib/contextlib.py", line 454, in __exit__    raise rest from excinst  File "/Volumes/RAMDisk/cpython/Lib/test/test_contextlib.py", line 1221, in test_exception_groups    raise eg_all()

in case of the newly added test.

This isn't a big problem because:

• the group's member exceptions contain pristine tracebacks, only the group itself contains extra frames; and
• theraise of the original group is still included in the traceback because we used.split() to create the new object.

Ideally, we wouldn't need this. However, the API of__exit__ makes it impossible to replace theExceptionGroup instance with another one, whileExceptionGroup itself makes its exceptions read-only.

Was there a specific reason to handleExceptionGroup but notBaseExceptionGroup?

I doubt it. Want to make a PR?