T-Mobile subscribers who have been itching to get their Samsung Galaxy S III upgraded to Android 4.1 Jelly Bean can now do so using a leaked over-the-air update file posted on the XDA-Developers forum. Android Police says that the file is an official T-Mobile OTA file that the carrier planned to use for the Galaxy S III soon, though the blog adds that this particular build still has some bugs related to Wi-Fi calling, the stock Web browser and the video player, so it likely isn’t the final version. Users who want to install the pre-release upgrade will need to root their devices first, Android Police says.