Race condition

[Johnlon]

If Dice.playdice() drops into the follow branch before the takeLeadership callback occurs then the program hangs without generating any dice rolls.

This is because the first block of code in follow() has a loop condition that never breaks out.
ie "while (ledgers == null) "

A potential solution is to change the condition to so that one the leadership
"while (ledgers == null && !leader)"

Or is this additional check wrong for some reason?

[Johnlon]

See pull request

[ivankelly]

@Johnlon for some reason github didn't send me a notification for this. I'm updating the tutorial for the new api, so will add this fix as I go.