This bug was initially created as a copy of Bug #1751175

I am copying this bug because: 
it also impacts RHEL 8.


Description of problem:
Since updating to python-requests 2.6.0.5.el7 (from 2.6.0.1.el7) the customer can no longer succesfully monitor our EMC Unity array using the check_unity scripts, because python's requests library no longer succesfully completes authentication to the array.

Root cause:
The auth header is dropped after the redirection, whereas the scheme/hostname/port is the same, but the default port has been explicitly mentioned in the request (http/80 or https/443).

Version-Release number of selected component (if applicable):
2.6.0.5

How reproducible:
See below

Steps to Reproduce:
1/ Create 2 subdirs in Apache root directory, foo and bar, protected with a basic AuthType.

2/ Write a small php script which does a redirection (without re-using the full URL from the $_SERVER global var).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<?php
header("Location: /bar", true, 301);
exit();
?>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

3/ Write a small python script to do a HTTP GET request with the default port explicitly mentioned.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
import requests
session = requests.Session()
session.auth = ('foo', 'foofoo')
response = session.get('http://192.168.122.12:80/foo')
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Actual results:
* Observe that it works with a previous version of python-requests (2.6.0-1 in this example)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ tshark port http
  4 0.000213603 192.168.122.1 -> 192.168.122.12 HTTP 299 GET /foo HTTP/1.1 
  6 0.000683891 192.168.122.12 -> 192.168.122.1 HTTP 591 HTTP/1.1 301 Moved Permanently  (text/html)
  8 0.001785669 192.168.122.1 -> 192.168.122.12 HTTP 300 GET /foo/ HTTP/1.1 
  9 0.002696987 192.168.122.12 -> 192.168.122.1 HTTP 341 HTTP/1.1 302 Found 
 10 0.003495810 192.168.122.1 -> 192.168.122.12 HTTP 299 GET /bar HTTP/1.1 
 11 0.003791207 192.168.122.12 -> 192.168.122.1 HTTP 590 HTTP/1.1 301 Moved Permanently  (text/html)
 12 0.004511989 192.168.122.1 -> 192.168.122.12 HTTP 300 GET /bar/ HTTP/1.1 
 13 0.005380148 192.168.122.12 -> 192.168.122.1 HTTP 342 HTTP/1.1 200 OK  (text/html)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

=> The authentication is still present after the HTTP 302 response:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hypertext Transfer Protocol
    GET /bar HTTP/1.1\r\n
        [Expert Info (Chat/Sequence): GET /bar HTTP/1.1\r\n]
            [Message: GET /bar HTTP/1.1\r\n]
            [Severity level: Chat]
            [Group: Sequence]
        Request Method: GET
        Request URI: /bar
        Request Version: HTTP/1.1
    Host: 192.168.122.12\r\n
    Connection: keep-alive\r\n
    Accept: */*\r\n
    Accept-Encoding: gzip, deflate\r\n
    Authorization: Basic Zm9vOmZvb2Zvbw==\r\n                          <===========
        Credentials: foo:foofoo                                        <===========
    User-Agent: python-requests/2.6.0 CPython/2.7.5 Linux/3.10.0-957.21.3.el7.x86_64\r\n
    \r\n
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* Observe that it does NOT work with python-requests-2.6.0-5:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  4 0.000106526 192.168.122.12 -> 192.168.122.12 HTTP 301 GET /foo HTTP/1.1 
  6 0.000980269 192.168.122.12 -> 192.168.122.12 HTTP 593 HTTP/1.1 301 Moved Permanently  (text/html)
  8 0.002424241 192.168.122.12 -> 192.168.122.12 HTTP 263 GET /foo/ HTTP/1.1 
  9 0.002551020 192.168.122.12 -> 192.168.122.12 HTTP 746 HTTP/1.1 401 Unauthorized  (text/html)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

=> In detail, the frames 8 without the auth header, which leads to the 401 response (frame 9).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hypertext Transfer Protocol
    HTTP/1.1 301 Moved Permanently\r\n
        [Expert Info (Chat/Sequence): HTTP/1.1 301 Moved Permanently\r\n]
            [Message: HTTP/1.1 301 Moved Permanently\r\n]
            [Severity level: Chat]
            [Group: Sequence]
        Request Version: HTTP/1.1
        Status Code: 301
        Response Phrase: Moved Permanently
    Date: Wed, 11 Sep 2019 08:55:41 GMT\r\n
    Server: Apache/2.4.6 (Red Hat Enterprise Linux) PHP/5.4.16\r\n
    Location: http://192.168.122.12/foo/\r\n
    Content-Length: 234\r\n
        [Content length: 234]
    Keep-Alive: timeout=5, max=100\r\n
    Connection: Keep-Alive\r\n
    Content-Type: text/html; charset=iso-8859-1\r\n
    \r\n
    [HTTP response 1/1]
    [Time since request: 0.000873743 seconds]
    [Request in frame: 4]
Line-based text data: text/html
    <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">\n
    <html><head>\n
    <title>301 Moved Permanently</title>\n
    </head><body>\n
    <h1>Moved Permanently</h1>\n
    <p>The document has moved <a href="http://192.168.122.12/foo/">here</a>.</p>\n
    </body></html>\n

Hypertext Transfer Protocol
    HTTP/1.1 401 Unauthorized\r\n
        [Expert Info (Chat/Sequence): HTTP/1.1 401 Unauthorized\r\n]
            [Message: HTTP/1.1 401 Unauthorized\r\n]
            [Severity level: Chat]
            [Group: Sequence]
        Request Version: HTTP/1.1
        Status Code: 401
        Response Phrase: Unauthorized
    Date: Wed, 11 Sep 2019 08:55:41 GMT\r\n
    Server: Apache/2.4.6 (Red Hat Enterprise Linux) PHP/5.4.16\r\n
    WWW-Authenticate: Basic realm="Restricted Files"\r\n
    Content-Length: 381\r\n
        [Content length: 381]
    Keep-Alive: timeout=5, max=99\r\n
    Connection: Keep-Alive\r\n
    Content-Type: text/html; charset=iso-8859-1\r\n
    \r\n
    [HTTP response 2/2]
    [Time since request: 0.000126779 seconds]
    [Prev request in frame: 4]
    [Prev response in frame: 6]
    [Request in frame: 8]
Line-based text data: text/html
    <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">\n
    <html><head>\n
    <title>401 Unauthorized</title>\n
    </head><body>\n
    <h1>Unauthorized</h1>\n
    <p>This server could not verify that you\n
    are authorized to access the document\n
    requested.  Either you supplied the wrong\n
    credentials (e.g., bad password), or your\n
    browser doesn't understand how to supply\n
    the credentials required.</p>\n
    </body></html>\n
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Expected results:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  4 0.000070794 192.168.122.12 -> 192.168.122.12 HTTP 301 GET /foo HTTP/1.1 
  6 0.001320044 192.168.122.12 -> 192.168.122.12 HTTP 593 HTTP/1.1 301 Moved Permanently  (text/html)
  8 0.003348937 192.168.122.12 -> 192.168.122.12 HTTP 302 GET /foo/ HTTP/1.1 
  9 0.004326371 192.168.122.12 -> 192.168.122.12 HTTP 355 HTTP/1.1 301 Moved Permanently 
 10 0.005436360 192.168.122.12 -> 192.168.122.12 HTTP 301 GET /bar HTTP/1.1 
 11 0.005847319 192.168.122.12 -> 192.168.122.12 HTTP 592 HTTP/1.1 301 Moved Permanently  (text/html)
 12 0.006739319 192.168.122.12 -> 192.168.122.12 HTTP 302 GET /bar/ HTTP/1.1 
 13 0.007998180 192.168.122.12 -> 192.168.122.12 HTTP 344 HTTP/1.1 200 OK  (text/html)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Additional info:
I provide the (modified) patch from the upstream which has been merged in the master branch as an attachment, it fixes the issue for me.

https://github.com/psf/requests/pull/4851

Please also note that the python3-requests coming with RHEL8.x is also impacted.