Python Error: Permission denied: '/usr/local/lib/python3.5/dist-packages/urllib3-1.24.1.dist-info'

[umsh1ume]

I was following this to setup wal-e with my staging server. In my step5 (see blog), when I enter
POSTGRES_VERSION=9.5 sudo -u postgres /usr/bin/envdir /etc/wal-e.d/env /usr/local/bin/wal-e backup-push /var/lib/postgresql/${POSTGRES_VERSION}/main,
I get following error :-
PermissionError: [Errno 13] Permission denied: '/usr/local/lib/python3.5/dist-packages/urllib3-1.24.1.dist-info'
I think this have something to do with me installing modules for both python2 and python3.
Please help