This is turning out be trickier than I ever thought.

fileno() returning b'' is just random error. The underlying issue is, *directly* reading from the fp of the socket() is returning a incomplete output at all times. The correct way to read the output is by using HTTPResponse read() method only it seems.

Here is a small snippet that will fail for every url.

from urllib.request import urlopen

import os

web = "http://www.example.org"

open_url = urlopen(web)
fd = open_url.fileno()
with os.fdopen(fd, 'rb') as f:
    file_read_len = len(f.read())

req = urlopen(web)
res_len = len(req.read())

assert file_read_len == res_len