lock wait changes

[dholth]

cache.py is the important change. Instead of bypassing Lock, we always try to get the lock. No timeout if we have an old result available.

Not sure if integer redis expire times are important, but I was getting some 'ResultError not an integer/number' errors from redis.

[bbangert]

Can you rebase this so I can easily apply it?

[dholth]

other one is more rebased but has no int() cast in lock.py