Issue
I can't get the python requests library, easy_install, or pip to work behind the corporate proxy. I can, however, get git to work.

How I got git working
I set the git proxy settings

git config --global http.proxy http ://proxyuser:proxypwd@proxy.server.com:8080


The corporate proxy server I work behind requires a user name and password and is indeed in the format

http: //username:passsword@ipaddress:port

I did not have to set the https.proxy



Things I have tried
(None of it has worked)
Environment Variables -  Pip and Requests library
Method 1

$ export HTTP_PROXY="http://username:passsword@ipaddress:port"
$ export HTTPS_PROXY="http://username:passsword@ipaddress:port"

Method 2

SET HTTP_PROXY="http://username:passsword@ipaddress:port"
SET HTTPS_PROXy="HTTPS_PROXY="http://username:passsword@ipaddress:port"


I have tried both restarting after setting the proxy variables, and trying them right after setting them
Checking the variables with the 'SET' command shows that both are set correctly 


Using Proxy Argument - Requests library
Creating a dictionary with the proxy information and passing it to requests.get()

proxies = {
   'http': 'http: //username:passsword@ipaddress:port',
   'https': 'http: //username:passsword@ipaddress:port'}
requests.get('http: //example.org', proxies=proxies)


Using Proxy Argument -  pip

pip install library_name -–proxy=http: //username:passsword@ipaddress:port
pip install library_name -–proxy=username:passsword@ipaddress:port


Results - Requests library
Response

Response [407]

Reason

'Proxy Authorization Required'

Header Information

{'Proxy-Authenticate': 'NTLM', 'Date': 'Fri, 05 May 2017 21:49:06 GMT', 'Cache-Control': 'no-cache', 'Pragma': 'no-cache', 'Content-Type': 'text/html; charset="UTF-8"', 'Content-Length': '4228', 'Accept-Ranges': 'none', 'Proxy-Connection': 'keep-alive'}


Results -  Pip

Retrying (Retry(total=4, connect=None, read=None, redirect=None)) after connec
  tion broken by 'ProxyError('Cannot connect to proxy.', OSError('Tunnel connectio
  n failed: 407 Proxy Authorization Required',))'


Note: In regards to this post, I have included a space in all my authentication 'links' between "http" and "://" because stackoverflow won't let me publish this with so many 'links'.
(I set up a new Stackoverflow account as my old account was a login via facebook thing and I can't access it from work)
I solved this by installing Fiddler and using it as my local proxy, while Fiddler itself used the corporate proxy.
Requests library & Pip Ntlm Proxy settings issues. - Python