title: Active Links in Gatsby seems broken with trailing slashes
body: <p>I want to highlight my item when I'm on the right page, so I'm using this code : </p>
  
  <pre><code>const isActive = ({ isCurrent }) =&gt; {
    return isCurrent ? { className: "active" } : null
  }
  &lt;Link getProps={isActive} to="/post"&gt;Articles&lt;/Link&gt;
  </code></pre>
  
  <p>It works for <code>/post</code> but doesn't work for <code>/post/</code></p>
  
  <p>How to fix that for both case please?</p>
  
  <hr>
  
  <p>I'm using : </p>
  
  <p><code>gatsby-link</code>: <a href="https://www.npmjs.com/package/gatsby-link" rel="nofollow noreferrer">https://www.npmjs.com/package/gatsby-link</a></p>
  
  <p>which use: <a href="https://reach.tech/router/example/active-links" rel="nofollow noreferrer">https://reach.tech/router/example/active-links</a></p>