setuptools fails in corporate MITM proxy with intermediate SSL cacerts

I was looking at the following piece of code in package_index.py:

        use_ssl = (
            verify_ssl
            and ssl_support.is_available
            and (ca_bundle or ssl_support.find_ca_bundle())
        )
        if use_ssl:
            self.opener = ssl_support.opener_for(ca_bundle)

I have added/appened the corporate CA certificates to /etc/ssl/cert.pem but setuptools never actually picks it up or uses it. Did anyone ever solve this?

FYI I am on a MacOS and using Anaconda with Python 3.6

Error that I get:

Download error on https://pypi.org/simple/: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:833) -- Some packages may not be found!
No local packages or working download links found for textacy
error: Could not find suitable distribution for Requirement.parse('textacy')

[bclodius]

@eholic thanks worked like a charm! In my case to make it more “portable” I used

import os
import setuptools.ssl_support
setuptools.ssl_support.cert_paths = [os.environ.get('SSL_CERT_FILE')]

Note to others: I had to use full path /home/<some_path> and not relative path for home directory ~.

[eholic]

Temporal solution of https://github.com/pypa/setuptools/issues/1543, https://github.com/pypa/setuptools/pull/1821 is overwriting cert_paths in setup.py.

from setuptools import setup
import setuptools.ssl_support
setuptools.ssl_support.cert_paths = ['/path/to/cafile']

setup()

https://github.com/pypa/setuptools/blob/17ad2b72ed29c91fd32e939abf3625314fe7c4ed/setuptools/ssl_support.py#L21