I encourage you to look at Michael Lewis's article[1]. This passage is relevant: "As Goldman hadn’t permitted him to release his debugged or improved code back to the public—possibly in violation of the original free licenses, which often stated that improvements must be publicly shared—the only way to get his hands on these was to take the Goldman code. That he had taken, in the bargain, some code that wasn’t open source, which happened to be contained in the same files as the open-source code, surprised no one. Grabbing a bunch of files that contained both open-source and non-open-source code was an efficient, quick, and dirty way to collect the open-source code, even if the open-source code was the only part that interested him."
[1] http://www.vanityfair.com/news/2013/09/michael-lewis-goldman...