Hello Marcos, I've done like you told me, I pasted these lines before the 'include' and I have a different error message, this time it is:
You don't have permission to access
on this server.
It does not tell me that URL is too long, but this time permission to access is forbidden.
I'm using Odoo-8.0-11.
To reproduce it:
You have to create a list view for Sale Order Lines, then go to this list view select all sale order lines, in my case it is 2515 lines, and print some html report.