--- a/entity.py	Wed Jun 16 09:33:04 2010 +0200
+++ b/entity.py	Wed Jun 16 09:53:17 2010 +0200
@@ -751,7 +751,10 @@
             return self.related_cache(rtype, role, entities, limit)
         except KeyError:
             pass
-        assert self.has_eid()
+        if not self.has_eid():
+            if entities:
+                return []
+            return self.empty_rset()
         rql = self.related_rql(rtype, role)
         rset = self._cw.execute(rql, {'x': self.eid})
         self.set_related_cache(rtype, role, rset)