[FIX] website: reset request attribute

When rerouting from a lang path token to the given route (eg:
/en_US/route_path to /route_path) it is better to keep request variable
clean.

opw-668563

addons/website/models/ir_http.py

@@ -158,6 +158,7 @@ class ir_http(orm.AbstractModel):
                     redirect.set_cookie('website_lang', request.lang)
                     return redirect
                 elif url_lang:
+                    request.uid = None
                     path.pop(1)
                     return self.reroute('/'.join(path) or '/')