MDEV-13306 JSON_CONTAINS returns wrong value.

        The 'value' state should be saved to be compared against the
        next array item.

mysql-test/r/func_json.result

@@ -152,6 +152,9 @@ json_contains('[{"abc":"def", "def":"abc"}]', '["foo","bar"]')
 select json_contains('[{"abc":"def", "def":"abc"}, "bar"]', '["bar", {}]');
 json_contains('[{"abc":"def", "def":"abc"}, "bar"]', '["bar", {}]')
 1
+select json_contains('[{"a":"b"},{"c":"d"}]','{"c":"d"}');
+json_contains('[{"a":"b"},{"c":"d"}]','{"c":"d"}')
+1
 select json_contains_path('{"key1":1, "key2":[2,3]}', "oNE", "$.key2[1]");
 json_contains_path('{"key1":1, "key2":[2,3]}', "oNE", "$.key2[1]")
 1

mysql-test/t/func_json.test

@@ -56,6 +56,7 @@ select json_contains('[1, {"a":1}]', '{}');
 select json_contains('[1, {"a":1}]', '{"a":1}');
 select json_contains('[{"abc":"def", "def":"abc"}]', '["foo","bar"]');
 select json_contains('[{"abc":"def", "def":"abc"}, "bar"]', '["bar", {}]');
+select json_contains('[{"a":"b"},{"c":"d"}]','{"c":"d"}');
 
 select json_contains_path('{"key1":1, "key2":[2,3]}', "oNE", "$.key2[1]");
 select json_contains_path('{"key1":1, "key2":[2,3]}', "oNE", "$.key2[10]");

sql/item_jsonfunc.cc

@@ -1011,6 +1011,8 @@ static int check_contains(json_engine_t *js, json_engine_t *value)
   case JSON_VALUE_ARRAY:
     if (value->value_type != JSON_VALUE_ARRAY)
     {
+      loc_js= *value;
+      set_js= FALSE;
       while (json_scan_next(js) == 0 && js->state != JST_ARRAY_END)
       {
         int c_level, v_scalar;
@@ -1021,6 +1023,11 @@ static int check_contains(json_engine_t *js, json_engine_t *value)
         if (!(v_scalar= json_value_scalar(js)))
           c_level= json_get_level(js);
 
+        if (set_js)
+          *value= loc_js;
+        else
+          set_js= TRUE;
+
         if (check_contains(js, value))
         {
           if (json_skip_level(js))