This occurs, for example, when searching for “macrumors.com” and adding
to the Feedbin account. All four feeds have a score of 0 since their
source is set as HTMLLink. This would also fix a case in which there are
two feeds: one with a negative score and one with a score of 0.
Since the method uses a Set the feed selected when there are multiple
feeds with an identical maximum score will be random.