Fix : Avoid user collision.

[guillaume-u]

When users are requesting a page in the same time, a user collision appears.

How to reproduce it :

• Login as user1 and get the cookie : user_session ;
• Login as user2 ;
• Start a loop, requesting a Shinken page with the user_session cookie (see above how to do it)
• Refresh your webpage (as user2), you will be connected as user1

How to make the loop request :

SHINKEN_URL="YOUR SHINKEN URL"
while true
do
  curl "$SHINKEN_URL/gotfirstdata" -H 'Cookie: user_session="YOUR SESSION COOKIE"'
done