[issue26804] Prioritize lowercase proxy variables in urllib.request

[Hans-Peter Jansen]

New submission from Hans-Peter Jansen:

During programming a function, that replaces a wget call, I noticed, that something is wrong with urllibs proxy handling. 

I usually use the scheme "http_proxy= wget -N -nd URL" when I need to bypass the proxy. Hence I was pretty confused, that this doesn't work with python(3). Creating an empty ProxyHandler isn't the real Mc Coy either. Diving into the issue, I found getproxies_environment, but couldn't make much sense out of its behavior, up until I noticed, that
my OS (openSUSE ) creates both variants of environment variables behind the scenes: uppercase and lowercase. 

Consequence: python3 needs the scheme "http_proxy= HTTP_PROXY= python3 ..."

Since I, like everyone else, prefer gentle tones over the loud, and want to spare this surprise for others in the future, I propose the attached patch.

Process environment variables in two passes, first uppercase, then lowercase, allowing an empty lowercase value to overrule any uppercase value.

Please consider applying this.

----------
components: Extension Modules
files: prioritize_lowercase_proxy_vars_in_urllib_request.diff
keywords: patch
messages: 263720
nosy: frispete
priority: normal
severity: normal
status: open
title: Prioritize lowercase proxy variables in urllib.request
type: behavior
versions: Python 3.5
Added file: http://bugs.python.org/file42516/prioritize_lowercase_proxy_vars_in_urllib_request.diff

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