[FIX] website_event: possible to order a negative quantity

bzr revid: chm@openerp.com-20140128170846-8elbtry7mzrdmeop

addons/website_event_sale/controllers/main.py

@@ -49,6 +49,7 @@ class website_event(website_event):
         for key, value in post.items():
             try:
                 quantity = int(value)
+                assert quantity > 0
             except:
                 quantity = None
             ticket_id = key.split("-")[0] == 'ticket' and int(key.split("-")[1]) or None