Lighttpd

I'm a Lighttpd maintainer for FreeBSD and I'm currently trying to make Lighttpd use Lua 5.2. For now, I've got a following patch:

--- src/mod_magnet.c.orig       2015-08-29 14:22:38.000000000 +0200
+++ src/mod_magnet.c    2015-09-29 11:46:30.312599419 +0200
@@ -24,6 +24,10 @@
 #define MAGNET_CONFIG_PHYSICAL_PATH "magnet.attract-physical-path-to" 
 #define MAGNET_RESTART_REQUEST      99

+#if LUA_VERSION_NUM >= 502
+#define LUA_GLOBALSINDEX LUA_REGISTRYINDEX
+#endif
+
 /* plugin config for all request/connections */

 static jmp_buf exceptionjmp;
@@ -688,7 +692,11 @@
         * get the environment of the function
         */

+#if LUA_VERSION_NUM >= 502
+       lua_getuservalue(L, -1); /* -1 is the function */
+#else
        lua_getfenv(L, -1); /* -1 is the function */
+#endif

        /* lighty.header */                                                                                                

@@ -738,7 +746,11 @@
         */

        force_assert(lua_isfunction(L, -1));
+#if LUA_VERSION_NUM >= 502
+       lua_getuservalue(L, -1); /* -1 is the function */
+#else
        lua_getfenv(L, -1); /* -1 is the function */
+#endif

        lua_getfield(L, -1, "lighty"); /* lighty.* from the env  */
        force_assert(lua_istable(L, -1));
@@ -988,7 +1000,11 @@
        lua_setmetatable(L, -2); /* setmetatable({}, {__index = _G}) (sp -= 1) */

+#if LUA_VERSION_NUM >= 502
+       lua_setuservalue(L, -2); /* on the stack should be a modified env (sp -= 1) */
+#else
        lua_setfenv(L, -2); /* on the stack should be a modified env (sp -= 1) */
+#endif

        errfunc = push_traceback(L, 0);
        if (lua_pcall(L, 0, 1, errfunc)) {

For now it compiles and after enabling mod_magnet Lighttpd starts fine, but using Lua makes Lighttpd return 503.