The difference is in what happens next. Find more sources would tend to get some more, and the rest would await sources.

In 4.8.1 and some of the 4.9 betas, resuming those would get some more. In 4.9.17 and other 4.9 betas, it has no effect -- it doesn't even show "connecting..." status however briefly. It seems to actually discard its knowledge of the source as soon as that source fails to respond even once -- which is bad, because failure to respond is often intermittent rather than indicating the host has become long-term unavailable.