Description:
------------
When decoded using json_decode and encoded back using json_encode some of the 
json elements are getting erroneously encoded. 

For eg: In the script below, the key named "message_tags" has the value 
{ "0": [ { "id": "663869041", "name": "Kiran Kumar Joseph", "type": "user", "offset": 0, "length": 18 } ] }

When decoded and encoded back into json, the message_tags' value changes to this
[[{"id":"663869041","name":"Kiran Kumar Joseph","type":"user","offset":0,"length":18}]]

The key "0" has been lost and an extra array has been used to wrap the original 
array. 
-------------------

I am using this package. php-5.4.9-nts-Win32-VC9-x86.zip.
Though the reproduction is on Windows, I have seen similar behavior on Linux 
also on older version of php. (PHP 5.2.10 (cli) (built: Jan  6 2011 10:28:31) on 
Linux SMP x86_64 x86_64 x86_64 GNU/Linux


Test script:
---------------
<?php
$str = '{ "id": "663869041_10151341204554042", "from": { "name": "Kiran Kumar Joseph", "id": "663869041" }, "to": { "data": [ { "name": "Kiran Kumar Joseph", "id": "663869041" } ] }, "message": "Kiran Kumar Joseph TEsting", "message_tags": { "0": [ { "id": "663869041", "name": "Kiran Kumar Joseph", "type": "user", "offset": 0, "length": 18 } ] }, "actions": [ { "name": "Comment", "link": "https://www.facebook.com/663869041/posts/10151341204554042" }, { "name": "Like", "link": "https://www.facebook.com/663869041/posts/10151341204554042" } ], "privacy": { "description": "Glisa Tk", "value": "CUSTOM", "friends": "SOME_FRIENDS", "networks": "", "allow": "100001436109139", "deny": "" }, "type": "status", "status_type": "mobile_status_update", "created_time": "2012-11-21T15:01:26+0000", "updated_time": "2012-11-21T15:01:26+0000", "comments": { "count": 0 } }';
$json = json_decode($str, true);
echo json_encode($json);
?>


Expected result:
----------------
I expect to see this output.

{ "id": "663869041_10151341204554042", "from": { "name": "Kiran Kumar Joseph", 
"id": "663869041" }, "to": { "data": [ { "name": "Kiran Kumar Joseph", "id": 
"663869041" } ] }, "message": "Kiran Kumar Joseph TEsting", "message_tags": { "0": 
[ { "id": "663869041", "name": "Kiran Kumar Joseph", "type": "user", "offset": 0, 
"length": 18 } ] }, "actions": [ { "name": "Comment", "link": 
"https://www.facebook.com/663869041/posts/10151341204554042" }, { "name": "Like", 
"link": "https://www.facebook.com/663869041/posts/10151341204554042" } ], 
"privacy": { "description": "Glisa Tk", "value": "CUSTOM", "friends": 
"SOME_FRIENDS", "networks": "", "allow": "100001436109139", "deny": "" }, "type": 
"status", "status_type": "mobile_status_update", "created_time": "2012-11-
21T15:01:26+0000", "updated_time": "2012-11-21T15:01:26+0000", "comments": { 
"count": 0 } }

Actual result:
--------------
I see this instead.

{"id":"663869041_10151341204554042","from":{"name":"Kiran Kumar 
Joseph","id":"663869041"},"to":{"data":[{"name":"Kiran Kumar 
Joseph","id":"663869041"}]},"message":"Kiran Kumar Joseph TEsting","message_tags":
[[{"id":"663869041","name":"Kiran Kumar 
Joseph","type":"user","offset":0,"length":18}]],"actions":
[{"name":"Comment","link":"https:\/\/www.facebook.com\/663869041\/posts\/101513412
04554042"},
{"name":"Like","link":"https:\/\/www.facebook.com\/663869041\/posts\/1015134120455
4042"}],"privacy":{"description":"Glisa 
Tk","value":"CUSTOM","friends":"SOME_FRIENDS","networks":"","allow":"1000014361091
39","deny":""},"type":"status","status_type":"mobile_status_update","created_time"
:"2012-11-21T15:01:26+0000","updated_time":"2012-11-21T15:01:26+0000","comments":
{"count":0}}