Laravel4 Composer update failed

I am working on a Laravel 4 project. When I try to update my packages with Composer it gets doctrine / collections but then it throws this error:

[Runtime Exception]
Failed to execute git status --porcelain --untracked-files=no

error: bad index file sha1 signature
fatal: index file corrupt

      

        
        
        
      

    

Exception Trace: http://pastebin.com/Js3nKrhy

I tried to remove the index in doctrine / collections, but then I tell him that the format is not correct in refs / remotes / origin / master.

Any idea how to fix this problem? Thank.