pkg_resources.DistributionNotFound: The 'pip==1.5.4' distribution was not found and is required by the application [duplicate]

Updated for 2017 (Ubuntu 17)

sudo apt-get purge python-pip
wget https://bootstrap.pypa.io/get-pip.py
sudo python get-pip.py
pip --version
rm get-pip.py

Faced the same problem with ubuntu 14.04 ,python2.7.6 and pip 1.5.4. I did this,

 sudo apt-get install --reinstall python2.7

To reinstall python (not necessary though)

 sudo apt-get purge python-pip

(removing python pip)

 wget https://raw.github.com/pypa/pip/master/contrib/get-pip.py

(download from this,this is upgraded version (9))

 sudo python get-pip.py
 sudo pip install package-name

This worked!

You could try the following command

$ hash -r