pip has dropped support for installing .egg-based packages when it stopped invoking setup.py install.
At some point pip will abandon support for detecting and uninstalling legacy .egg-based packages too.

If you reach this issue from the pip deprecation message, it is likely that your Python environment has packages that have been installed with setup.py install, easy_install, or an older pip version.

The recommended action is to uninstall the package and reinstall it with a recent pip.