ScrambleSuit session ticket handshake failures

At first I thought this was an obfsclient problem, but I can get the same behaviour to happen with obfsproxy.

How to reproduce:

1. Do a UniformDH handshake to obtain a session ticket.
2. Kill tor/obfsproxy
3. Wait 30 mins
4. Try to connect (SessionTicket will be used)
5. The session ticket handshake fails.

Looking at the obfsproxy logs (with the debug level), it is pulling the previously saved ticket from disk and sending a handshake message after doing deriving all the keys.

The only "real" bridge I tested against was the one that phw runs (identifies itself as ScrambleSuit0) that was posted to tor-talk back in October, since I'm not sufficiently human to solve the BridgeDB captcha, so this may be a issue with the version of the code that's running on the bridge, and not something that I will run into in the wild.

When I run a local bridge, I can't reproduce this behaviour either.

(On a side note, obfsproxy does not appear to implement a timeout, it takes 5 mins for tor to give up, and tor does not appear to retry when a UniformDH handshake would succeed. From a user's perspective, the UX isn't great if their ticket happens to expire.)