Comment 1 for bug 409405

The change (in the pastebin) is to check that result is actually present there.

I'd like to confirm whats going on; there may be a serious issue, or it might be shallow. What do you mean by 'tearDown being called from a callback' - could you get a backtrace of the error (e.g. by wrapping the access in
try:
except KeyError:
    import pdb;pdb.set_trace()

and when you get into pdb do
bt\n

-Rob