this change removes raising an exception if an attribute is not found:
hg log -r 3164
Änderung:        3164:24476db8872f
Nutzer:          Richard Jones <richard@users.sourceforge.net>
Datum:           Mon Feb 14 04:53:41 2005 +0000
Zusammenfassung: nicer error looking up values of None (response to 
[SF#1108697]
@@ -1565,7 +1568,8 @@
         ''' return a new HTMLItem '''
        #print 'Link.getattr', (self, attr, self._value)
         if not self._value:
-            raise AttributeError, "Can't access missing value"
+            msg = self._('Attempt to look up %(attr)s on a missing value')
+            return MissingValue(msg%locals())
         i = HTMLItem(self._client, self._prop.classname, self._value)
         return getattr(i, attr)

I'm observing the bad behaviour the first time after
Änderung:        3913:00896a2acaa5
Nutzer:          Justus Pendleton <jpend@users.sourceforge.net>
Datum:           Thu Sep 20 23:44:58 2007 +0000
Zusammenfassung: clean up query display of "Private to you" items

No obvious problem found, it probably did not get tested well enough 
after the rev3913 change. 

I've decided for the smaller fix, because it limits possible undetected side 
effect, changing  LinkHTMLProperty to a new-style class.
Committed with rev4864:f630eb0adcee

Thanks again David!