[FIX] pos: check constraint on session instead of uid (eg: runbot import demo data with uid=1 but other user_id

bzr revid: mat@openerp.com-20131014121959-fp4gs26xh8cdte1w

addons/point_of_sale/point_of_sale.py

@@ -271,7 +271,7 @@ class pos_session(osv.osv):
             # open if there is no session in 'opening_control', 'opened', 'closing_control' for one user
             domain = [
                 ('state', 'not in', ('closed','closing_control')),
-                ('user_id', '=', uid)
+                ('user_id', '=', session.user_id.id)
             ]
             count = self.search_count(cr, uid, domain, context=context)
             if count>1: