Compatibility with pyserial 2.3-1

[coblee]

I'm running MPBM on raspberry pi. Debian Squeeze does not come with python3-serial. The pyserial on it is version 2.3-1 and it's a little different. In order to make your code compatible with 2.3-1, you just need to change this line:

https://github.com/TheSeven/Modular-Python-Bitcoin-Miner/blob/testing/modules/theseven/bflsingle/bflsingleworker.py#L157

and remove the None at the end. In pyserial 2.6, it defaults to None if you don't pass in anything. So this change should work for both versions.

[TheSeven]

Yes, I'm aware of this... Will probably change that during the next days while having a look at some recent regressions on the testing branch.