embedgist2.js

$(document).ready(function() {
    var embedGist = function () {
        $('a[href^="https://gist.github.com"]').each(function(i) {
            if (writeCapture) {
                var wrapper = $("<div></div>");
                wrapper.insertAfter(this);
                
                writeCapture.html(wrapper[0], '<script src="'+$(this).attr("href")+'.js"></script>');    
                $(this).remove();
            } else {
                window.setTimeout(waitForFnc,50);
            }
        });
    }
    
    embedGist();
});

theme.html

<!-- Add the following lines to theme's html code right before </body> -->
<script src="http://code.jquery.com/jquery-2.1.0.min.js"></script>
<script src="http://static.tumblr.com/fpifyru/VCxlv9xwi/writecapture.js"></script>
<script src="http://static.tumblr.com/zx0ox2p/Jr9n13uql/embedgist2.js"></script>

<!--
  Usage: just add a link to your gist
  Example: <a href="https://gist.github.com/1395926">https://gist.github.com/1395926</div>
-->

I do not know what happened, but it stopped working in my Tumblr. Do you know what did happen? Thanks.