aliases expanding aliases: a bug?

[Jay Berkenbilt <ejb@xxxxxx>]

I just downloaded zsh 4.3.10, and I am able to reproduce this problem
with that version.  It appears that if an alias ends with a space,
arguments that themselves happen to be aliases are expanded, at least in
some cases.  Here's an example:

   $ zsh -f
   host% alias a1='echo'
   host% alias a2='echo '
   host% alias moo=quack
   host% a1 moo
   moo
   host% a2 moo
   quack

I can't imagine that this is desirable or intended behavior.  It's also
hard for me to see why one would have to have a trailing space in an
alias that was expected to take arguments, but regardless, it still
seems like a possible bug.

Comments?

-- 
Jay Berkenbilt <ejb@xxxxxx>