Play nice with Backbone.history.root when attaching pushstate click handler

backbone_pushstate_router.js

    // Only need this for pushState enabled browsers
    if (Backbone.history && Backbone.history._hasPushState) {
      var $document = $(window.document);
      var openLinkInTab = false;

      // Links like <a href="some/thing/here"> are relative to the page.
      // We want to run these links thru the router
      var is_relative_to_page = function(href) {
        return href.match(/^\/|(http:|https:|ftp:|mailto:|javascript:)/) === null;
      };

      // If a link is relative, or it contains the current history.root, consider the URL routable locally
      // Unless it has a fragment. Let hrefs with a fragment continue normally
      var is_routable = function(href) {
        return href.indexOf("#") === -1 && (is_relative_to_page(href) || href.indexOf(Backbone.history.root) > -1);
      };

      $document.keydown(function(e) {
        if (e.ctrlKey || e.keyCode === 91) {
          openLinkInTab = true;
        }
      });

      $document.keyup(function(e) {
        openLinkInTab = false;
      });

      $document.on("click", "a", function(e) {
        var href =  $(this).attr("href");
        if (is_routable(href)) {
          e.preventDefault();
          Backbone.history.navigate(href, true);
        }
      });
    }