Pet Daemon: test formula write failure and recovery

[kriskowal]

What is the Problem Being Solved?

We do not currently have a test (and our implementation probably doesn’t gracefully handle) from failure to write a formula and restarting the daemon to recover. It probably should resume from the state before the formula was committed.

[fsaad]

Great point: we can also save entropy, since the FLDR "entropy gap" generally gets worse with increasing sum of integers m.