path forward for pip-style vcs or url identifiers?

[cburroughs]

This is already a todo [1] but I was unsure about the right approach. Pip has it's own code [2] to support this and does not appear to be part of a shared packaging library.
(A) Would depending on pip directly be okay?
(B) If not, is vendoring/forking the pip code acceptable?

[1] https://github.com/pantsbuild/pants/blob/master/src/python/pants/backend/python/python_requirement.py#L34

[2] https://github.com/pypa/pip/blob/13d43e3af8b5c8e8c7c66dde8a9f76b340697c3e/pip/vcs/git.py

[benjyw]

Supported via the fact that pex now delegates to pip.

[Eric-Arellano]

Not quite. See #3063 (comment).

[stuhood]

@Eric-Arellano : Do they both still need to be open, or can we track this with #3063?

[Eric-Arellano]

Fair, I think #3063 covers enough of this.