title: How to prevent homebrew from upgrading a package?
body: <p>I'm wondering if there's any means to prevent Homebrew from upgrading a particular package ? Yesterday I went for a <code>brew upgrade</code> which updated the lua package from 5.1 to 5.2. It broke one of the projects I'm working on those days so I had to downgrade the lua package today when I noticed it. </p>
  
  <p>I'd like this not to happen again, and I guess Homebrew must provide this kind of feature, but I didn't find anything about it in the documentation. Do you have any clue ?</p>