python pip install without cache

From documentation at https://pip.pypa.io/en/latest/reference/pip_install.html#caching: Starting with v6.0, pip provides an on by default cache which functions similarly to that of a web browser. While the cache is on by default and is designed do the right thing by default you can disable the cache and always access PyPI by utilizing the --no-cache-dir option. pip install pillow --no-cache-dir