For future reference: How to properly modify the URL of a urllib.request.Request

gistfile1.py

import urllib.request
from urllib.parse import urlsplit, urlunsplit, unquote

class ModifyUrlHandler(urllib.request.BaseHandler):
    def __init__(self, target):
        x = urlsplit(target)
        self.full_url = urlunsplit(x._replace(fragment=""))
        self.fragment = x.fragment
        #Remove port from x.netloc if present for origin_req_host
        self.origin_req_host = x.netloc.partition(":")[0]
        self.host = unquote(x.netloc)
        self.selector = x.path
        if x.query:
            self.selector += "?" + x.query
        if not self.selector:
            self.selector = "/"
        self.type = x.scheme

    def http_request(self, req):
        req.full_url = self.full_url
        req.fragment = self.fragment
        req.origin_req_host = self.origin_req_host
        req.host = self.host
        req.selector = self.selector
        req.type = self.type
        req.unredirected_hdrs["Host"] = self.host
        return req

if __name__ == "__main__":
    opener = urllib.request.build_opener(ModifyUrlHandler("http://httpbin.org/get?x=a"))
    r = opener.open("http://www.google.com")
    print(r.read().decode())