Test new dependency resolver in pip 20.2

[icemac]

As many people nowadays install Zope using pip, we should test the upcoming "next-generation dependency resolver" to prevent problems later on.

See an excerpt of a mail from [pypi-announce] for details:

NOTICE: This release includes the beta of the next-generation dependency resolver. 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 test it with the --use-feature=2020-resolver flag. 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-20-2-2020.

The new dependency resolver is off by default because it is not yet
ready for everyday use.

[jugmac00]

I tested it with Zope 4.5 and it worked out.

Compared to the current standard resolver (11 secs) the new one took 59 sec on my local dev box.

This is a known problem/limitation as the new resolver works more thoroughly.

[icemac]

I tested it with Zope 4.5 and it worked out.

Thank you.

Compared to the current standard resolver (11 secs) the new one took 59 sec on my local dev box.

Yikes!

This is a known problem/limitation as the new resolver works more thoroughly.

Should we give this as feedback to the pip developers?

[jugmac00]

There is already
pypa/pip#8675
and
pypa/pip#8664

I also reported it on Twitter https://twitter.com/jugmac00/status/1290366233473318913 and the developers are aware of the situation.

As far as I know... the old resolver just skips some checks, as it is not able to do all checks properly.

The new resolver does it "right", and thus it inherently needs more time.

[icemac]

Thank you. I consider this issue as resolved for now.