title: How do I match all % except one that is followed by s?
body: <p>What is the regex for matching all percent-like characters except one that is followed by <code>s</code>?</p>
  
  <p>I want to escape all <code>%</code> with <code>%%</code> but I do not want <code>%s</code> to become <code>%%s</code>. I am using Ruby to replace all occurrences of <code>%</code> in this case.</p>