Merge pull request #2442 from creative-commoners/pulls/4.2/extensible-sitetree-hints-cache-key

NEW Add updateHintsCacheKey extension point to fix invalid caching

code/Controllers/CMSMain.php

@@ -2272,7 +2272,11 @@ class CMSMain extends LeftAndMain implements CurrentPageIdentifier, PermissionPr
      */
     protected function generateHintsCacheKey($memberID)
     {
-        return md5($memberID . '_' . __CLASS__);
+        $baseKey = $memberID . '_' . __CLASS__;
+
+        $this->extend('updateHintsCacheKey', $baseKey);
+
+        return md5($baseKey);
     }
 
     /**