ImportError: No module named _io in ubuntu 14.04

After I upgraded my Ubuntu 12.04 server to 14.04, my django app stopped working. I tried to debug it and got this error message:

ImportError: No module named _io

And the reason of this is the python of my virtualenv (2.7.3) and the server's python version (2.7.6) was mismatched. So, what I did to fix the issue was overriding the virtualenv's python binary with the new one:

cp `which python2.7` myenv/bin/python