matcher-list doesn't work with some completers?

[Mikael Magnusson <mikachu@xxxxxxxxx>]

Hi,

mkdir 'a directory'
zsh -f
autoload -Uz compinit; compinit -D
zstyle ':completion:*' matcher-list 'm:{a-zA-Z}={A-Za-z}' +'l:|=* r:|=*'
ls dir<tab> #works
du dir<tab> #nothing
zstyle ':completion:*' matcher-list 'm:{a-zA-Z}={A-Za-z} l:|=* r:|=*'
ls dir<tab> #works
du dir<tab> #works

Obviously the latter style is useless in practice, but why doesn't the
first one work always? The _mkdir completer has the same issue as _du,
but _rar seems to work. I looked at them and I can't figure out what
the difference is. This is not a new issue, but I'm not sure when it
started happening. The _du in 4.3.6 works, but the _mkdir does not.
Copying the older _du doesn't seem to make any difference so it is
probably Something Else[tm].

-- 
Mikael Magnusson