title: Unable to start services using homebrew
body: <p>MacOs 10.15.1<br>
  Ruby 2.4.4<br>
  Homebrew 2.1.16</p>
  
  <p>I am currently experiencing issues when attempting to start any services through Homebrew. 
  Output for any attempt is as follows:</p>
  
  <pre><code>$ brew services start postgresql@9.5
  Error: undefined method `resolve_alias' for Formula:Class
  /usr/local/bin/brew-services.rb:154:in `service'
  /usr/local/bin/brew-services.rb:203:in `check'
  /usr/local/bin/brew-services.rb:193:in `run!'
  /usr/local/bin/brew-services.rb:397:in `&lt;top (required)&gt;'
  /usr/local/Homebrew/Library/Homebrew/utils.rb:79:in `require'
  /usr/local/Homebrew/Library/Homebrew/utils.rb:79:in `require?'
  /usr/local/Homebrew/Library/Homebrew/brew.rb:108:in `&lt;main&gt;'
  </code></pre>
  
  <p>Edit 11/27/19:
  Brew Doctor output</p>
  
  <pre><code>$ brew doctor
  Please note that these warnings are just used to help the Homebrew maintainers
  with debugging if you file an issue. If everything you use Homebrew for is
  working fine: please don't worry or file an issue; just ignore this. Thanks!
  
  Warning: You have unlinked kegs in your Cellar.
  Leaving kegs unlinked can lead to build-trouble and cause brews that depend on
  those kegs to fail to run properly once built. Run `brew link` on these:
    php
  </code></pre>