fix lua nil for nested values

Also for #43

Author: alicebob

integration/script_test.go

@@ -18,6 +18,8 @@ func TestEval(t *testing.T) {
 		succ("EVAL", "return {ARGV[1]}", 0, "first\nwith\nnewlines!\r\r\n\t!"),
 		succ("EVAL", "return redis.call('GET', 'nosuch')==false", 0),
 		succ("EVAL", "return redis.call('GET', 'nosuch')==nil", 0),
+		succ("EVAL", "local a = redis.call('MGET', 'bar'); return a[1] == false", 0),
+		succ("EVAL", "local a = redis.call('MGET', 'bar'); return a[1] == nil", 0),
 
 		// failure cases
 		fail("EVAL"),

lua.go

@@ -163,7 +163,7 @@ func redisToLua(l *lua.LState, res []interface{}) *lua.LTable {
 	for _, e := range res {
 		var v lua.LValue
 		if e == nil {
-			v = lua.LValue(nil)
+			v = lua.LFalse
 		} else {
 			switch et := e.(type) {
 			case int64: