Skip install on tox pylint

[scop]

Proposed change

We're not operating on the installed package anyway, and necessary
dependencies are handled with tox deps.

As a nice bonus side effect, doing this sidesteps breakage caused by
pip's (up to 20.2.2 at least) behavior of prepending site-packages to
sys.path in certain cases, which in turn results in failures e.g. if a
version of typing that is incompatible with the (now overridden)
stdlib is installed there. And that combined with also pip's behavior
of installing a default build system consisting of setuptools and
wheel under the hood when it sees our pyproject.toml without a
build-system defined would provoke the breakage before we have a
chance to uninstall typing. (There are ways around this too, but
skipping the install makes the issue moot at least with our current
dependency set.)

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

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To help with the load of incoming pull requests:

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[balloob]

We are operating on the installed deps, as pylint will look into the installed deps to make sure objects exist / method names are correct.

[scop]

Sure, but the deps are installed through requirements files. HA itself does not need to be installed, nor dependencies through setup.py as as side effect of doing so.

[scop]

Specifically here,

core/tox.ini

Line 23 in 34c2579

-r{toxinidir}/requirements_all.txt

(actually way more deps are installed than what would get installed as side effect of installing HA anyway, which is what the skip_install prevents, and this is fine)

[balloob]

I should know better than to doubt your changes 😉 👍

[scop]

Thanks, but nah, more than one pair of eyes is always welcome :)