Is this a bug in Cwm?

I've been experimenting with "recursive" rules in Cwm, and get some 
unexpected results:

   http://www.ninebynine.org/SWAD-E/Intro.html#CwmRulesExperiments

My test file is:
   http://www.ninebynine.org/SWAD-E/Scenario-HomeNetwork/PlayRules.n3

Which essentially reduces to this test case:

[[
{
   ?A rule:append ( [ daml:first ?H ; daml:rest ?T ] ?T1 ) .
}
log:implies
{
   ?A daml:first ?H ;
      daml:rest  [ rule:append ( ?T ?T1 ) ] .
} .

:A1 rule:append ( ( "L11" "L12" "L13" ) "L14" ) .
]]

#g


-------------------
Graham Klyne
<GK@NineByNine.org>