[IronPython] Iteration via __getitem__ doesn't work in the Visual Studio debugging environment

[Tony Meyer]

I have this program:

class A(object):
    def __init__(self):
        self.data = range(5)
    def __getitem__(self, item):
        return self.data[item]
a = A()
for v in a:
    print v

i.e. there's a class that gets iteration through the __getitem__
method.  When run with IronPython in the shell (or with CPython), you
get the expected result:

C:\>"c:\Programs\IronPython 2.7\ipy.exe" Program.py
0
1
2
3
4

C:\>c:\Python27\python.exe Program.py
0
1
2
3
4

Underneath, of course, this is doing a[0], a[1], a[2], a[3], a[4], and
stopping when a[5] raises an IndexError.

When I run this in Visual Studio, the debugger catches the IndexError,
so this doesn't work.  It seems like the exception should be allowed
to propagate further, so that the iteration works - but maybe this
just isn't compatible with how the debugger works?

(It's easy enough to fix this by defining _iter__, of course).

Is this a bug?  Or just a limitation of how the debugging environment works?

Thanks,
Tony