diff -r 5a0b02f37b23 -r 19861294506f entity.py
--- a/entity.py	Fri Jun 19 08:47:05 2009 +0200
+++ b/entity.py	Fri Jun 19 09:19:27 2009 +0200
@@ -398,7 +398,7 @@
         path = etype.lower()
         if mainattr != 'eid':
             value = getattr(self, mainattr)
-            if value is None:
+            if value is None or unicode(value) == u'':
                 mainattr = 'eid'
                 path += '/eid'
             elif needcheck: