As it happens, I have real life C code that is impacted by this change. Lanes module replaces the original require() function with a wrapper that calls it inside a mutex-protected section (see luaG_new_require in
https://github.com/LuaLanes/lanes/blob/master/src/state.c). The way the wrapper is written, it only expects a single result from require, and therefore fails to propagate all returned values to the caller as it should. Whether Lua code breaks because of this remains conjectural (nobody complained yet).
