inconsistent uninstall/install behavior

• Pip version: 9.0.1
• Python version: 2.7
• Operating system: Linux

Description:

I’m trying to install numpy from a local git repo, after first manually uninstalling it to work around another pip issue. It looks like the metadata for installed packages that pip keeps is used in a way that allows inconsistencies - it tells me both that numpy is not installed and that it is installed.

What I’ve run:

pip uninstall numpy
...
Proceed (y/n)? y
    Successfully uninstalled numpy-1.13.0

$ pip uninstall numpy
Cannot uninstall requirement numpy, not installed

$ pip install . --user
Processing /home/rgommers/Code/numpy
  Requirement already satisfied (use --upgrade to upgrade): numpy==1.13.0 from file:///home/rgommers/Code/numpy in /home/rgommers/Code/numpy

Forcing an upgrade succeeds, but the above is still a real issue.

$ pip install . --user -U
Processing /home/rgommers/Code/numpy
Installing collected packages: numpy
  Running setup.py install for numpy ... done
Successfully installed numpy-1.13.0

[pradyunsg]

FWIW, I just tried out pip install ., python setup.py install and python setup.py develop for a basic package foo;

pip uninstall foo detected and uninstalled them one by one over 3 runs.

[elmerehbi]

Solved with pip install --upgrade --force-reinstall --user scikit-learn. I simply added the --user flag.