python::pip ensure => latest triggers refresh on each puppet run for some packages

[gdubicki]

Affected Puppet, Ruby, OS and module versions/distributions

• Puppet: 5.5.2
• Ruby: included in Puppet 5
• Distribution: Centos 7
• Module version: 2.1.0

How to reproduce (e.g Puppet code you use)

Try to use python::pip with ensure => 'latest' using https://github.com/devpi/devpi as PyPi mirror/own repo for packages that contain mixed case letters in their names.

What are you seeing

Package is reinstalled on every puppet run and refresh is triggered, which causes unnecessary changes in reports and, what is worse, services restarts.

What behaviour did you expect instead

Package should not be updated if it's already in the latest version. No change should be reported for the resource and no refresh should be triggered.

Any additional information you'd like to impart

Please see devpi/devpi#592 for info how I tried to fix it on devpi side. Apart from getting to conclusion that this is hard to fix it there I realized that as pip team is considering to remove pip search altogether (see pypa/pip#5216), perhaps even better solution for this problem would be to stop using pip search on puppet-python side. This could also fix issues like #350.

[gdubicki]

I created a PR for this here #434 .

[gdubicki]

Actually, as test that is failing here #445 shows, python::pip with ensure => 'latest' using regular PyPi repo for a package with uppercase letter and "_" in its name also triggers refresh with every puppet run.