Odoo won't start after pysftp installed

Environment

UBUNTU 16.04
Odoo 9

Problem

Today I came across the situation where after installing pysftp suddenly I won’t be able to start odoo again. I have tried to do

service odoo restart
service odoo stop ; service odoo start

When I have tried to uninstall pysftp, I was having SSL_ST_INIT error

Copy to Clipboard

root@erp:~# pip uninstall pysftp
Traceback (most recent call last):
 File "/usr/bin/pip", line 9, in 
 from pip import main
 File "/usr/lib/python2.7/dist-packages/pip/__init__.py", line 13, in 
 from pip.exceptions import InstallationError, CommandError, PipError
 File "/usr/lib/python2.7/dist-packages/pip/exceptions.py", line 6, in 
 from pip._vendor.six import iteritems
 File "/usr/lib/python2.7/dist-packages/pip/_vendor/__init__.py", line 64, in 
 vendored("cachecontrol")
 File "/usr/lib/python2.7/dist-packages/pip/_vendor/__init__.py", line 36, in vendored
 __import__(modulename, globals(), locals(), level=0)
 File "/usr/share/python-wheels/CacheControl-0.11.5-py2.py3-none-any.whl/cachecontrol/__init__.py", line 9, in 
 File "/usr/share/python-wheels/CacheControl-0.11.5-py2.py3-none-any.whl/cachecontrol/wrapper.py", line 1, in 
 File "/usr/share/python-wheels/CacheControl-0.11.5-py2.py3-none-any.whl/cachecontrol/adapter.py", line 3, in 
 File "/usr/share/python-wheels/requests-2.9.1-py2.py3-none-any.whl/requests/__init__.py", line 53, in 
 File "/usr/share/python-wheels/urllib3-1.13.1-py2.py3-none-any.whl/urllib3/contrib/pyopenssl.py", line 54, in 
 File "/usr/lib/python2.7/dist-packages/OpenSSL/__init__.py", line 8, in 
 from OpenSSL import rand, crypto, SSL
 File "/usr/lib/python2.7/dist-packages/OpenSSL/SSL.py", line 118, in 
 SSL_ST_INIT = _lib.SSL_ST_INIT
AttributeError: 'module' object has no attribute 'SSL_ST_INIT'