[tahoe-dev] end of compatibility with Twisted 2.4?

[Brian Warner]

> So I downgraded that last one -- my own workstation -- to Twisted 2.4 and I
> learned that the Tahoe unit tests don't currently pass with Twisted 2.4.

For reference, I think the test failure is a due to an interaction between
Foolscap's CopiedFailure processing, Twisted's Failure class (in particular
the .parents value), and Zooko's recent "ServerFailure" exception class. I
need to investigate further, but I think that Twisted-2.4.x had a bug in
Failure which was fixed in later versions, and Foolscap is relying upon the
non-buggy behavior, but it wasn't exposed until ServerFailure was added.

No comment yet on supporting/dropping Twisted-2.4.x, I'll think about that
more tomorrow.

cheers,
 -Brian