Comment 6 for bug 1549393

Setting an initial review target of 2.next, but as a bug fix, this can likely be pointed at 2.10-rc when that milestone gets created.

Applied fix and tested against concerto bibs (and some LOC imported records) and the stock OpenLibrary provider and nothing blows up (aka, I still see covers). Will try out some other providers later, but on the surface, this change seems fine.