fixed NameError for filename
fixed NameError for filename

I declared filename before it is used so it should pass the doctests
Disassem/urllib3,urllib3/urllib3,haikuginger/urllib3,Lukasa/urllib3,sigmavirus24/urllib3,haikuginger/urllib3,urllib3/urllib3,sigmavirus24/urllib3,Lukasa/urllib3,Disassem/urllib3