Handle a looping scenario (a > b > c > a).

modules/islandora_breadcrumbs/src/IslandoraBreadcrumbBuilder.php

@@ -79,6 +79,12 @@ class IslandoraBreadcrumbBuilder implements BreadcrumbBuilderInterface {
     $breadcrumb->addLink(Link::createFromRoute($this->t('Home'), '<front>'));
 
     $chain = array_reverse($this->utils->findAncestors($node, [$this->config->get('referenceField')], $this->config->get('maxDepth')));
+
+    // XXX: Handle a looping breadcrumb scenario by filtering the present
+    // node out and then optionally re-adding it after if set to do so.
+    $chain = array_filter($chain, function ($link) use ($nid) {
+      return $link !== $nid;
+    });
     if ($this->config->get('includeSelf')) {
       array_push($chain, $node);
     }