Rails 3.2: invalid %-encoding (100%)

I started getting exception notifications recently from the server
just about the time I upgraded to Rails 3.2. I don't know if that is a
coincidence or not. Evidently some robot is hitting my site with:

mydomain.com?iframe=true&width=100%&height=100%

and that is throwing an exception.

I have two questions:

1) First, just out of curiosity, who puts
"iframe=true&width=100%&height=100%" on their requests, and why?

2) Second, obviously I don't want a 500 error. How can I filter out
the parameters before it crashes?

Thanks!

Having the same problem.
These requests are from people who use webproxies.

I keep seeing on github that similar issues with
URI.decode_www_form_component have been solved a while ago, yet it still
happens to me. Any ideas how to handle this gracefully before getting a
server error?