stepmania/stepmania — pull request #46 by kyzentun (2014-02-13 00:38:44+00:00)
Title: Made SOUND:PlayMusicPart pass on the loop and applyRate args.

Spoiler: applyRate doesn't actually make it apply a rate mod to the music part, and figuring out why would mean digging deeper into GameSoundManager. This just covers passing in the arguments from Lua.