Removing support for git+git@ VCS requirement scheme

What’s the problem this feature will solve?

In addition to VCS requirements which have the form of a proper URL, pip also partially supports a git specific scheme of the form [e-mail]:user/repo.git. As currently documented, this scheme is supported for editable installs only.

Supporting this scheme has a number of drawbacks:

• This creates confusion when people try to use it without the --editable option (#2994, #6293).
• This also creates bugs, such as when adding the commit to the requirement, pip freeze generates requirements that pip cannot process (#2038).
• This specific format is not a proper URL, making such requirement impossible to translate to PEP 440 direct URL references.
• it would seem that support for this format is rather accidental in the pip code base (https://github.com/pypa/pip/issues/2038#issuecomment-570065043, also illustrated by the fact that link.is_vcs returns False for such pseudo-URLs), and properly supporting it everywhere would be very complex.

This scheme is easily replaced by URLs such as

• git+https://[e-mail]/…
• git+ssh://[e-mail]/…
• git+git://[e-mail]/… (insecure)

Describe the solution you’d like

Deprecate support for this format during one year, then remove it (#7543).

Alternative solutions

• fix issues as they are discovered (e.g. support this format for non-editable uses, make pip freeze transform the reference to a supported format)
• do nothing, document the exceptions

[lericson]

Eh, I gave up on Windows compatibility a long time ago 😃

[lericson]

Never mind, I found a workaround using the environment variable support in requirements.txt:

-e git+file://${PWD}@mydep#egg=mydep