1. We would find a flow.
2. refine_flow would reduce it so it doesn't deliver enough.
3. So we need to find another, but we are at the limit.
4. So we remove the flow we found.
5. Goto 1.
This can be fixed by disabling a channel which we caused us to reduce the flow,
so we should always make forward progress.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Fixed: Plugins: `askrene` could enter an infinite loop when maxparts is restricted.
03d38b612d