title: Symfony 2 logs me out between prod and dev environnements
body: <p>I'm having a stange issue with a symfony app I upgraded from 2.0 to 2.3.</p>
  
  <p>I also upgraded fosuserbundle to match my sf2 version.</p>
  
  <p>Before that upgrade, i could log in in dev environnement for example, and if I decided to switch to the prod front controller, I was still logged in.</p>
  
  <p>Since I upgraded, when I switch from dev to prod I'm not authenticated on both environnements.</p>
  
  <p>I can't even log in manually on both, because when I log in on prod it logs me out from dev and in the other way around.</p>
  
  <p>Is it a normal behavior which was added in symfony or fosuserbundle and is there a way to disable that behavior ?
  If not, has someone encountered the same problem ?</p>
  
  <p>Thank you for reading and spending some time on this ! </p>