Undefined Index: unique in FeedsCSVParser.inc

On import I get an error that the index 'unique' is undefined. When I do dsm($mapping) it shows source, target and unique for all. I should also point out that I am using #860748: Config for mappers? also, in case that matters. In any case, it looks as though the index exists in the array, but for whatever reason something is going wrong.

According to the dev output, unique contains 'FALSE' and is Boolean.