Allow to submit form after browser back button is pressed

9f85120 added a check to prevent the form from being submitted
multiple times. This check is based on the presence of a class
that is added to the form when it is submitted the first time.

In some situations, the class is not removed from the form when the
user navigates back using the browser back button. This prevents the
form from being submitted again.

This commit adds a check to remove the class from the form when the
page is loaded.

share/static/js/util.js

@@ -1036,6 +1036,11 @@ jQuery(function() {
             form.addClass('rt-form-submitted');
         });
     });
+    // Clean up the class on page load in case user hit browser back button
+    // Listen for the back button event (popstate)
+    jQuery(window).on('popstate', function(event) {
+        jQuery('form').removeClass('rt-form-submitted');
+    });
 });
 
 function filterSearchResults (type) {