zsh-3.1.x cdmatch problem

[Paul Lew <lew@xxxxxxxxxxxxxxxxxx>]

I am trying switch from 3.0.x to 3.1.x but one problem is really
bugged me: The completion after 'cd' command generated:

    zsh: bad math expression: unbalanced stack

This does not happen for 3.0.x, the function cdmatch is the one from
standard distribution:

(3)ezdzit lew Src>>> function cdmatch {
emulate -R zsh
setopt localoptions
local narg pref cdp
read -nc narg
read -Ac pref
cdp=(. $cdpath)
reply=(${^cdp}/${pref[$narg]%$2}*$2(-/DN^M:t))
return
}

If I get rid of the reply= line, the error message disappeared but
there is also no reply list for the completion.

Any idea what wrong here?  Thanks in advance.