windows proxy settings taken only partly

do run python 2.7/3.7 on a windows 7 host.
This host is AD managed. As part of the group policy the internet settings are set to automatically proxy configuration with an wpad.dat file at the AD server.
The configuration works. cos IE and Chrome can reach external and internal hosts. Some of the internal are excluded from proxy via no proxy rules inside the dat file.

But on python with requests im not able to reach the internal addresses which are excluded via the proxy file rules. Python always tries to get the data from the proxy.

The only solution was an extra environmental variable NO_PROXY with the ips not to be reached via the proxy.

These excluded IPs are common IPs and not private ! (90.0.0.0/8) is part of the wpad.dat exclusion

Expected Result

either no proxy or all proxy settings should taken into account.

Actual Result

every requests traffic is placed on the proxy
urllib3 works as expected

Reproduction Steps

import requests
import urllib3
http1 = urllib3.PoolManager()
r1 = http.request('GET', 'http://90.0.11.253:43001/')
r1.status 

r2 = requests.get('http://90.0.11.253:43001/')
r2.status_code

r1==r2 must be true but isnt

System Information

$ python -m requests.help

C:\Users\iwetzel\AppData\Local\Programs\Python\Python37-32>python -m requests.help
{
  "chardet": {
    "version": "3.0.4"
  },
  "cryptography": {
    "version": ""
  },
  "idna": {
    "version": "2.8"
  },
  "implementation": {
    "name": "CPython",
    "version": "3.7.1"
  },
  "platform": {
    "release": "7",
    "system": "Windows"
  },
  "pyOpenSSL": {
    "openssl_version": "",
    "version": null
  },
  "requests": {
    "version": "2.21.0"
  },
  "system_ssl": {
    "version": "1010009f"
  },
  "urllib3": {
    "version": "1.24.3"
  },
  "using_pyopenssl": false
}

This command is only available on Requests v2.16.4 and greater. Otherwise,
please provide some basic information about your system (Python version,
operating system, &c).

Start by running the Windows 7 reproduction and comparing the proxy behavior of requests with urllib3 for the listed 90.0.11.253 URL and WPAD exclusion. Trace how the requests call obtains proxy settings versus the explicit NO_PROXY workaround. Done means the documented WPAD no-proxy rule is honored, or the limitation and supported configuration are clearly established with a regression test.