Given other comments in this thread, it means (1) viewing the original work (in this case, the source code), (2) making superfluous changes to avoid literal copying (changing variable names, find-replace company name, etc), and (3) passing this off as original.

It sounds like it's not "You made a knockoff, that's 'non-literal copying,'", it's "You made a literal copy, changed a couple of things, and called it yours."