Python/pip behind corporate firewall

[Tong Sun]

Our corporate firewall, Zscaler, is blocking my `pip install`.

Anyone has a similar situation?

I've already installed pipsi & py37-certifi:

```
sudo port -N install pipsi py37-certifi

$ python -m certifi
/opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/certifi/cacert.pem
```

and I've also update the Zscaler certificate into this CA Store,

cat ZscalerRootCertificate-2048-SHA256.crt >> $(python -m certifi)

as per https://community.zscaler.com/t/installing-tls-ssl-root-certificates-to-non-standard-environments/7261

but still, I can't pip install anything. For e.g.:

$ sudo -H pip3 install --upgrade certifi
WARNING: Retrying (Retry(total=4, connect=None, read=None,
redirect=None, status=None)) after connection broken by
'SSLError(SSLCertVerificationError(1, '[SSL:
CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get
local issuer certificate (_ssl.c:1123)'))': /simple/certifi/

Any Python users here?
thx