I had a routing problem, and wrote a simple unit test which passed. So
I wrote one which copied the failure case (and importantly, had a non-1
fee factor), which triggerd it.
In that real example, we underflowed which resulted in us not finding
a route. Simply don't consider routes which are infinite.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Rusty Russell