[Twisted-Python] Making a duck-typed traceback from a Failure

[Jonathan Lange]

Hello,

I've recently been doing work with Twisted tests from within the Zope
testrunner. It's a real pain because if the tests or their callbacks
raise exceptions, no traceback gets given to the result object. See
#2495.

The fix I've uploaded doesn't actually help me. By the time the result
object gets the failures, they've been cleaned with cleanFailure --
Failure.tb is None and everything is a string.

Is it possible to make a duck-typed traceback from a cleaned Failure?
I haven't really looked into it, but I can't think of why not off the
top of my head. Granted I ran out of thought gluons a couple of hours
ago.

cheers,
jml