Alternative solution.

Rely on `site.url` which is different for production. In that case do nothing with the search result, otherwise when in development remove our url from it.

_includes/docs-sidebar.html

 <form class="bd-search d-flex align-items-center">
-  <input type="search" class="form-control" id="search-input" placeholder="Search..." aria-label="Search for..." autocomplete="off" data-baseurl="{{ site.baseurl }}/docs/{{ site.docs_version }}">
+  <input type="search" class="form-control" id="search-input" placeholder="Search..." aria-label="Search for..." autocomplete="off" data-siteurl="{{ site.url }}">
   <button class="btn btn-link bd-search-docs-toggle d-md-none p-0 ml-3" type="button" data-toggle="collapse" data-target="#bd-docs-nav" aria-controls="bd-docs-nav" aria-expanded="false" aria-label="Toggle docs navigation">
     {%- include icons/menu.svg width="30" height="30" -%}
   </button>

assets/js/src/application.js

@@ -115,8 +115,13 @@
         },
         transformData: function (hits) {
           return hits.map(function (hit) {
-            var baseurl = document.getElementById('search-input').getAttribute('data-baseurl')
-            hit.url = hit.url.replace('https://getbootstrap.com' + baseurl, baseurl)
+            // When in production, return the result as is,
+            // otherwise remove our url from it.
+            var siteurl = document.getElementById('search-input').getAttribute('data-siteurl')
+            var urlRE = /^https?:\/\/getbootstrap\.com/
+
+            hit.url = siteurl.match(urlRE) ? hit.url : hit.url.replace(urlRE, '')
+
             return hit
           })
         },