Shortcut the case where the path searched for is longer than anything indexed.

lib/python/Products/PluginIndexes/PathIndex/PathIndex.py

@@ -174,6 +174,10 @@ class PathIndex(Persistent, SimpleItem):
 
         comps = filter(None, path.split('/'))
         
+        if level + len(comps) - 1 > self._depth:
+            # Our search is for a path longer than anything in the index
+            return IISet()
+
         if len(comps) == 0:
             return IISet(self._unindex.keys())