[IMP] website_crm: set utm medium override Website

To set utm values (medium, source and campaign) on created record, the
system use default function which check cookies and other funny things.

But for website form creating a record, the medium value would be
overrided always to Website whilst that should be a fallback (and the
set medium should have priority).

closes odoo#10848
opw-668853

addons/website_crm/models/crm_lead.py

@@ -4,5 +4,9 @@ class Lead(models.Model):
     _inherit = 'crm.lead'
 
     def website_form_input_filter(self, request, values):
-        values.setdefault('medium_id', request.registry['ir.model.data'].xmlid_to_res_id(request.cr, SUPERUSER_ID, 'utm.utm_medium_website'))
+        values['medium_id'] = (
+                values.get('medium_id') or
+                self.default_get(['medium_id']).get('medium_id') or
+                self.sudo().env['ir.model.data'].xmlid_to_res_id('utm.utm_medium_website')
+        )
         return values