pip 20.3 release (heads-up for potential disruption)

[Sumana Harihareswara]

On 11/30/20 8:33 AM, Sumana Harihareswara wrote:
> On behalf of the Python Packaging Authority, I am pleased to announce 
> that we have just released pip 20.3, a new version of pip. You can 
> install it by running `python -m pip install --upgrade pip`.
> 
> This is an important and disruptive release -- we explained why in a
> blog post last year 
> https://pyfound.blogspot.com/2019/12/moss-czi-support-pip.html . We even 
> made a video about it: https://www.youtube.com/watch?v=B4GQCBBsuNU .
> 
> Blog post with details: 
> https://pyfound.blogspot.com/2020/11/pip-20-3-new-resolver.html
> 
> Highlights include:
> 
> * **DISRUPTION**: Switch to the new dependency resolver by
>      default. Watch out for changes in handling editable
>      installs, constraints files, and more:
> 
> https://pip.pypa.io/en/latest/user_guide/#changes-to-the-pip-dependency-resolver-in-20-3-2020 
> 
> 
> * **DEPRECATION**: Deprecate support for Python 3.5 (to be removed in
>      pip 21.0)
> 
> * **DEPRECATION**: pip freeze will stop filtering the pip, setuptools,
>      distribute and wheel packages from pip freeze output in a future
>      version. To keep the previous behavior, users should use the new
>      `--exclude` option.
> 
> * Support for PEP 600: Future ‘manylinux’ Platform Tags for Portable
>    Linux Built Distributions.
> 
> * Add support for MacOS Big Sur compatibility tags.
> 
> The new resolver is now *on by default*. It is significantly stricter
> and more consistent when it receives incompatible instructions, and
> reduces support for certain kinds of constraints files, so some
> workarounds and workflows may break. Please see our guide on how to
> test and migrate, and how to report issues: 
> https://pip.pypa.io/en/latest/user_guide/#changes-to-the-pip-dependency-resolver-in-20-3-2020 
> . You can use the deprecated (old) resolver, using the flag
> `--use-deprecated=legacy-resolver`, until we remove it in the pip 21.0
> release in January 2021.
> 
> In pip 21.0 we will also remove support for Python 2.7.
> 
> You can find more details (including deprecations and removals) in the
> changelog https://pip.pypa.io/en/stable/news/ , and you can find 
> thank-yous and instructions on reporting issues at 
> https://pyfound.blogspot.com/2020/11/pip-20-3-new-resolver.html .
> 
> Thank you,
> Sumana Harihareswara
> pip project manager
> Changeset Consulting
> https://changeset.nyc


Incidentally, I should have mentioned in my previous email:

pip 20.3 turned the new resolver on by default for Python 3 users. When 
users use pip 20.3 in a Python 2 environment, the old dependency 
resolver is still the default. Python 2 users should also note that pip 
21.0 in January will remove Python 2 support: 
https://pip.pypa.io/en/latest/development/release-process/#python-2-support 
.

-- 
Sumana Harihareswara