I've made a litte patch for Wesnoth long time ago. While the codebase wasn't small it didn't really matter that much. There are a lot of things in the game (animation, networking, ui, game logic) that are separated enough that it's not that much of a big code mess like most commercials projects you see.
Also the C++ used isn't the monster from under the bed people tell tales of. It's mostly simple OOP/procedural code using boost library.
It's not that difficult to learn enough C++ to be useful.
Agreed. Wesnoth's codebase is pretty straightforward, "dumb" C++ (and I mean that as a compliment--smart C++ can get you in trouble really easily). I think most of the bits of it I've wandered through are pretty good examples of how to write C++ for games without killing yourself.
It's shocking how much a wannabe game dev that looks like Philip Seymour Hoffman's younger sister can learn about enterprise development too, when they've never actually worked a day in their life at a typical enterprise shop.
Also the C++ used isn't the monster from under the bed people tell tales of. It's mostly simple OOP/procedural code using boost library.
It's not that difficult to learn enough C++ to be useful.