Sometimes, you can't install an external dependency with pip and have to include it directly within your project, such as in the following cases:
- When you have a patched third-party app where you yourself fixed a bug or added a feature that did not get accepted by project owners
- When you need to use private apps that are not accessible at the Python Package Index (PyPI) or public version control repositories
- When you need to use legacy versions of dependencies that are not available at PyPI anymore
Including external dependencies in your project ensures that whenever a developer upgrades the dependent modules, all of the other developers will receive the upgraded version in the next update from the version control system.
