title: brew install grep --with-default-names gives "invalid option" error
body: <p>I am trying to replace the default version of grep: (BSD grep 2.5.1-FreeBSD) </p>
  
  <p>on my mac (Mojave 10.14.6) </p>
  
  <p>and when I run the recommended command to replace the BSD version with the gnu version: </p>
  
  <p><code>brew install grep --with-default-names</code></p>
  
  <p>I get the aforementioned error. Anyone seen this and know the workaround?</p>