W1Sensor sometimes gets stuck

[michaelcadilhac]

First off, what a brilliant piece of software; I love the coding style and the architecture of the project.

I've been running tfbrew for a few hours now, extending it as I needed. At some point, the W1Sensor got stuck at 4°, and the hysteresis logic had my kegerator run to -11°C before I realized. Looking at /sys/bus/w1/devices/ID/w1_slave, the temperature was correctly listed at -11°C, but it seems that for one probe, the file wasn't there.

As a result, the asyncio task crashed from the pattern matching done in readTemp.

I've modified the function like this, and haven't had a problem since.