Fix brew cask doctor for non-standard installation location

[lucafavatella]

• Have you followed the guidelines in our Contributing document?
  • I ran brew update several times.
  • brew doctor shows one warning Warning: Your Homebrew's prefix is not /usr/local.
    • (BTW I would need to find out how to make the exit status of brew doctor not to be non-zero only for the non-standard prefix - for automated check.)
  • This is not a formula-specific issue.
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
  • Please refer to commit message. Please let me know if you want me to move symptom&analysis from commit message to PR description.
• Have you written new tests for your changes? Here's an example.
  • No. I had a look at the tests in Library/Homebrew/test/cmd/doctor_spec.rb though I am not sure how I would write a test for this fix. Guidance welcome.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew tests with your changes locally?
  • I get one failure - irrespective of my changes:

  1) OS::Mac::language can be parsed by Locale::parse
     Failure/Error: expect { Locale.parse(subject.language) }.not_to raise_error

       expected no Exception, got #<Locale::ParserError: '' cannot be parsed to a Locale> with backtrace:
         # ./locale.rb:15:in `parse'
         # ./test/os/mac_spec.rb:19:in `block (4 levels) in <top (required)>'
         # ./test/os/mac_spec.rb:19:in `block (3 levels) in <top (required)>'
         # ./test/spec_helper.rb:117:in `block (2 levels) in <top (required)>'
         # ./vendor/bundle/ruby/2.3.0/gems/rspec-retry-0.6.0/lib/rspec/retry.rb:120:in `block in run'
         # ./vendor/bundle/ruby/2.3.0/gems/rspec-retry-0.6.0/lib/rspec/retry.rb:109:in `loop'
         # ./vendor/bundle/ruby/2.3.0/gems/rspec-retry-0.6.0/lib/rspec/retry.rb:109:in `run'
         # ./vendor/bundle/ruby/2.3.0/gems/rspec-retry-0.6.0/lib/rspec_ext/rspec_ext.rb:12:in `run_with_retry'
         # ./vendor/bundle/ruby/2.3.0/gems/rspec-retry-0.6.0/lib/rspec/retry.rb:34:in `block (2 levels) in setup'
         # ./vendor/bundle/ruby/2.3.0/gems/rspec-wait-0.0.9/lib/rspec/wait.rb:46:in `block (2 levels) in <top (required)>'
     # ./test/os/mac_spec.rb:19:in `block (3 levels) in <top (required)>'
     # ./test/spec_helper.rb:117:in `block (2 levels) in <top (required)>'
     # ./vendor/bundle/ruby/2.3.0/gems/rspec-retry-0.6.0/lib/rspec/retry.rb:120:in `block in run'
     # ./vendor/bundle/ruby/2.3.0/gems/rspec-retry-0.6.0/lib/rspec/retry.rb:109:in `loop'
     # ./vendor/bundle/ruby/2.3.0/gems/rspec-retry-0.6.0/lib/rspec/retry.rb:109:in `run'
     # ./vendor/bundle/ruby/2.3.0/gems/rspec-retry-0.6.0/lib/rspec_ext/rspec_ext.rb:12:in `run_with_retry'
     # ./vendor/bundle/ruby/2.3.0/gems/rspec-retry-0.6.0/lib/rspec/retry.rb:34:in `block (2 levels) in setup'
     # ./vendor/bundle/ruby/2.3.0/gems/rspec-wait-0.0.9/lib/rspec/wait.rb:46:in `block (2 levels) in <top (required)>'

I think the test is making a wrong assumption on system configuration, or my system has broken language config:

$ defaults read -g AppleLanguages
2018-06-10 00:37:23.861 defaults[17535:160332]
The domain/default pair of (kCFPreferencesAnyApplication, AppleLanguages) does not exist

---

[lucafavatella]

I see codecov/patch job failed but I have no idea whether it is expected, and it is unclear to me how I may address it. These changes delete some unused code so I would expect code coverage percentage to increase rather.

[reitermarkus]

I think the test is making a wrong assumption on system configuration, or my system has broken language config:

The latter, mine shows

$ defaults read -g AppleLanguages
(
    "de-AT",
    de,
    en
)

Try adding/deleting a system language in System Preferences.

[reitermarkus]

This should also use user_tilde.

[lucafavatella]

Addressed. Rebased on master and force-pushed.

[reitermarkus]

Thanks, @lucafavatella, nice cleanup!