This isn't so much a bug with zsh-completion (it could happen with any third
party completions).
The problem is this: If you happen to compile your functions (zcompile). Then
the functions added by zsh-completion will not be made available to your shell,
that is until you delete .zcompdump{.zwc} and recompile.
With zsh-completion installed and site-fucntions in my $fpath the new
completions were not recognized until I had deleted .zcompdump{.zwc}, restarted
the shell and recompiled the .z*.{zwc}
Similarly to the update from (if my memory is correct) zsh 4.1 to 4.2 there is
very little that the package manager could do in this regard, but it's maybe a
good idea to add this to the README or to pass this information to the user
during install in the form of and einfo.
