collapse_excgroups context manager removing exception context

[ccrims0n]

collapse_excgroups used in the BaseHTTPMiddleware has the following code:

try:
    yield
except BaseException as exc:
    if has_exceptiongroups:
        while isinstance(exc, BaseExceptionGroup) and len(exc.exceptions) == 1:
            exc = exc.exceptions[0]  # pragma: no cover

    raise exc from None

The last line of this function updates the __context__ of the exception object, exc. This also adds unnecessary context Another exception happened during the handling of exception.

I am not sure if this is by design but this is unnecessary and can obscure details of how the exception was raised.

Fix
Both the cases, exception group object and the exception object should be handled separately. Only raise should be used to re-raise caught exception. For the exception group, the right way needs to be figured out.