Pip SSL Error But Curl Works - Windows Behind Corporate Proxy w/ CNTLM

I am trying to get pip running on my windows machine behind a corporate proxy. I am using a CNTLM proxy to add authentication.

The following command works:

curl --cacert C:\Users\xxxxxxx\curl-ca-bundle.crt http://ift.tt/Icu3cE

but the following command doesn't:

pip install --cert C:\Users\xxxxxx\curl-ca-bundle.crt install six

I have set the CNTLM proxy settings in the HTTP_PROXY and HTTPS_PROXY environment variables, and can confirm both pip and curl are using them (changing the env variable to an invalid address yields an error). The cert file is the Mozilla trust store with my corporate Root cert appended. If curl is fine using it I would assume it is fine to use with pip.

The Pip log is revealing a TLSv1 alert decode error:

------------------------------------------------------------
C:\Python27\Scripts\pip run on 03/02/15 09:12:03
Downloading/unpacking six
  Getting page http://ift.tt/1mx1jPv
  Could not fetch URL http://ift.tt/1mx1jPv: connection error: [SSL: TLSV1_ALERT_DECODE_ERROR] tlsv1 alert decode error (_ssl.c:581)
  Will skip URL http://ift.tt/1mx1jPv when looking for download links for six
  Getting page http://ift.tt/Xn8D49
  Could not fetch URL http://ift.tt/Xn8D49: connection error: [SSL: TLSV1_ALERT_DECODE_ERROR] tlsv1 alert decode error (_ssl.c:581)
  Will skip URL http://ift.tt/Xn8D49 when looking for download links for six
  Cannot fetch index base URL http://ift.tt/Xn8D49
  URLs to search for versions for six:
  * http://ift.tt/1mx1jPv
  Getting page http://ift.tt/1mx1jPv
  Could not fetch URL http://ift.tt/1mx1jPv: connection error: [SSL: TLSV1_ALERT_DECODE_ERROR] tlsv1 alert decode error (_ssl.c:581)
  Will skip URL http://ift.tt/1mx1jPv when looking for download links for six
  Could not find any downloads that satisfy the requirement six
Cleaning up...
  Removing temporary dir c:\users\xxxxxxx\appdata\local\temp\pip_build_xxxxxx...
No distributions at all found for six
Exception information:
Traceback (most recent call last):
  File "C:\Python27\lib\site-packages\pip\basecommand.py", line 122, in main
    status = self.run(options, args)
  File "C:\Python27\lib\site-packages\pip\commands\install.py", line 278, in run
    requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
  File "C:\Python27\lib\site-packages\pip\req.py", line 1177, in prepare_files
    url = finder.find_requirement(req_to_install, upgrade=self.upgrade)
  File "C:\Python27\lib\site-packages\pip\index.py", line 277, in find_requirement
    raise DistributionNotFound('No distributions at all found for %s' % req)
DistributionNotFound: No distributions at all found for six

Any suggestions as to how to get around this error? I would even be opening to disabling SSL if pip allowed it.

N.B I'm running pip 1.5.6 w/ python 2.7.9