The wrong usage of unfree-redistributable fixed in
ea242619fb can be explaind by unclear
documention, specifically the section in the nixpkgs manual describing
generic licenses it is written to use attributes from `stdenv.lib.licenses`
but in the list the strings form was documented without quotation marks.
This confuses people because the package builds fine locally but failes
the tests on travis-ci.
7f7ebe5bf6