Example pip9 dependency resolution problem with packages: cherrypy, cheroot, six

[matt-hammond-001]

See pypa/pip#4887 for example of dependency resolution problem with pip9 between cherrypy, cheroot and six. To reproduce:

$ pip uninstall cherrypy cheroot six
$ pip install six==1.10.0
$ pip install cherrypy==11.0.0
$ pip check
cheroot 5.10.0 has requirement six>=1.11.0, but you have six 1.10.0.

( Re-reporting, as requested in https://github.com/pypa/pip/issues/988#issuecomment-360846457 )

[pradyunsg]

Thanks for filing this @matt-hammond-bbc!

I think this is already handled cleanly. I'll add a test for this and make sure.

[matt-hammond-001]

That is good to hear! Thanks @pradyunsg

[nlhkabu]

@matt-hammond-bbc the pip team is currently working on the new dependency resolver and wants to better understand the circumstances under which the resolver fails.

To help us, would you be able to :

1. Try the new resolver (use version 20.1, run --unstable-feature=resolver)
2. Break it :P
3. File an issue

You can find more information and more detailed instructions here

Thanks!