prevent automatic checkout visual studio 2012 git

Hi,

The files are getting checked out automatically without any confirmations. I am using GIT as source control. Gone through the below link

http://msdn.microsoft.com/en-us/library/4x00bk11(v=vs.90).aspx

But I am unable to find the "Environment" link. Under "Source Control", I have only "Plug in selection". I am using "Visual Studio tools for GIT"

Thanks in advance

Arun