luarocks: fix usage of local configs

Skipping of load local configuration files will result in problems and
loss of backward compatibility.

Part of tarantool/tt#1003

src/luarocks/core/cfg.lua

@@ -727,14 +727,10 @@ function cfg.init(detected, warning)
       exit_ok, exit_err, exit_what = nil, err, "config"
    end
 
-   if hardcoded.FORCE_HARDCODED then
-      util.deep_merge(cfg.variables, hardcoded)
-   end
-
    -- Load user configuration file (if allowed)
    local home_config_ok
    local project_config_ok
-   if not hardcoded.FORCE_CONFIG and not hardcoded.FORCE_HARDCODED then
+   if not hardcoded.FORCE_CONFIG then
       local env_var   = "LUAROCKS_CONFIG_" .. cfg.lua_version:gsub("%.", "_")
       local env_value = os.getenv(env_var)
       if not env_value then
@@ -786,6 +782,10 @@ function cfg.init(detected, warning)
       end
    end
 
+   if hardcoded.FORCE_HARDCODED then
+      util.deep_merge(cfg.variables, hardcoded)
+   end
+
    -- backwards compatibility:
    if cfg.lua_interpreter and cfg.variables.LUA_BINDIR and not cfg.variables.LUA then
       cfg.variables.LUA = dir.path(cfg.variables.LUA_BINDIR, cfg.lua_interpreter)