keepalive bug when access resp.url

[hysia]

in urllib2

resp = addinfourl(fp, r.msg, req.get_full_url())
resp.url has value

but when keepalive installed to opener, resp._url instead of resp.url and this will make programe error

[hysia]

BTW，other bugs just diff with https://github.com/sqlmapproject/sqlmap/blob/master/thirdparty/keepalive/keepalive.py

[wikier]

@hysia can you give a try to the current HEAD of 0.6.dev0?