Adaptation manager has ill-defined `sort` usage.

In `AdaptationManager._adapt` there's a line:

```
edges.sort(cmp=_by_weight_then_from_protocol_specificity)
```

But the `_by_weight_then_from_protocol_specificity` function doesn't give a transitive relation, so the results of the sort are undefined. It's not clear to me how important the sort order is here.