Cann't download css files

[dongweiming]

Install notebook but display this error:

    Complete output from command /Users/dongweiming/.virtualenvs/jupyter_notebook/bin/python -c "import setuptools, tokenize; __file__='/Users/dongweiming/.virtualenvs/jupyter_notebook/src/nbconvert/setup.py'; exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" develop --no-deps:
    running develop
    running css
    Failed to download css from https://cdn.jupyter.org/notebook/4.0.0-dev/style/style.min.css: [Errno socket error] [Errno 1] _ssl.c:504: error:14077438:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert internal error
    error: None

    ----------------------------------------
    Command "/Users/dongweiming/.virtualenvs/jupyter_notebook/bin/python -c "import setuptools, tokenize; __file__='/Users/dongweiming/.virtualenvs/jupyter_notebook/src/nbconvert/setup.py'; exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" develop --no-deps" failed with error code 1 in /Users/dongweiming/.virtualenvs/jupyter_notebook/src/nbconvert

i have to use http:// instead of https://

[takluyver]

This looks like a duplicate of #21, though it's interesting that it works with http. Let's continue the discussion on that.