ipdb: support for chained exceptions #13982

This is a common pattern to enrich an exception with more information:

def foo(x):
    try:
        bar(x)
    except Exception as e:
        raise ValueError("foo(): bar failed") from e
def bar(x):
    1/x

This is common when a second exception occurs during exception handling:

def foo(x):
    try:
        bar(x)
    except Exception as e:
        raise ValueError("some other error")
def bar(x):
    1/x

In both cases, ipdb (and pdb) wont let us step up the stack from to find the error in bar. While python 3.11 has Exception.add_note, there will continue to be lots of code using the methods above (and its not always practical to use this).

Example:

Can we enhance ipdb to handle both cases?