A command line tool, to simplify vendoring pure Python dependencies.
pip had a "home-grown" setup for vendoring dependencies. The invoke task grew in complexity to over 500 lines and, at some point, became extremely difficult to improve and maintain.
This tool is based off the overgrown invoke task, breaking it out into a dedicated codebase with the goal of making it more maintainable and reusable. This also enabled independent evolution of this codebase and better access to infrastructure (like dedicated CI) to ensure it keeps working properly.
This tool has no stability promises -- it has only one intended user: pip. There may be unannounced changes to this codebase at any time, as long as the intended user (i.e. the pip project) is prepared for those changes.
As a general rule of thumb, if the project is going to be a PyPI package, it should not use this tool.
Many downstream redistributors have policies against this kind of bundling of dependencies, which means that they'll patch your software to debundle it. This can cause various kinds of issues, due to violations of assumptions being made about where the dependencies are available/which versions are being used. These issues result in difficult-to-debug errors, which are fairly difficult to communicate with end users.
pip is a very special case with a thorough rationale for vendoring/bundling dependencies with itself.
Check the Contributing guide.