title: pug variable not evaluated on a href tag
body: <p>In my Express JS web app, a <code>login</code> route renders some variables to the login pug view.</p>
  
  <p>In <code>login.js</code></p>
  
  <pre><code>router.get('/login', function(req, res, next) {
    var locations = ["Location 1", "Location 2"];
    var count = 0;
    var title = 'Login';
    console.log("req.originalUrl=" + req.originalUrl);
  
    res.render('login', {
             title: title, // Give a title to our page
             jsonData: locations, // Pass data to the View
             count: locations.length,
             originalUrl: req.originalUrl
        });
  });
  </code></pre>
  
  <p>In <code>login.pug</code></p>
  
  <pre><code>extends layout
  
  block content
    div(class='container mt-3')
      h2 Welcome to #{title}, #{count}, #{originalUrl}
      a(class="btn btn-primary" href="/location/new" role="button") NEW
      br
      br
      ul#locList(class='list-group')
        for location in jsonData
          li(class="list-group-item")
            a(href='#{originalUrl}' + '?' + location, class='list-group-item list-group-item-action')
              h2=location
  </code></pre>
  
  <p>The <code>originalUrl</code> variable in the <code>a href</code> was not evaluated as '<code>http://localhost:3000/login?Location%201</code>', but '<code>http://localhost:3000/login#{originalUrl}?Location%201</code>' instead.</p>
  
  <p>Then I had to change it to '<code>a(href=originalUrl + '?' + location, class='list-group-item list-group-item-action')</code>' in order to make it work.</p>
  
  <p>In a nutshell, <code>a(href='#{originalUrl}')</code> does not work while <code>a(href=originalUrl)</code> works, for <code>a href</code>.</p>
  
  <p>However, the same variable was correctly evaluated at line '<code>h2 Welcome to #{title}, #{count}, #{originalUrl}</code>' as '<code>Welcome to Login, 2, /login</code>'.</p>
  
  <p>How was the same variable evaluated differently on <code>a href</code> from <code>h2</code>?</p>