If that happens, try
1) reinstall node.js first
2) put this into your .bash_profile:
The cause might be that the particular instance of Python is running from a protected space in the fs.
PATH="/System/Library/Frameworks/Python.framework/Versions
/2.7/bin:${PATH}"
export PATH
Python seems to operate from 2 directories: /usr/bin
and the aforementioned
(I was able to download with the latter)