[This thread went into my spam folder for some reason.]

On Apr 12, 2015 4:03 PM, "Han Pingtian" <hanpt@linux.vnet.ibm.com> wrote:
>
> POSIX_BUILTINS <K> <S>
>        [...]  Parameter  assignments  specified
>        before  shell  functions and special builtins are kept after the
>        command completes unless the special builtin  is  prefixed  with
>        the  command  builtin.
> [...]
> But looks like the parameter assignment before "command special-builtin"
> is kept even though POSIX_BUILTINS has been set

Indeed I can confirm, it appears this either was never working or has been
broken by some recent change.

The default zsh behavior when posixbuiltins is not set, is to not keep the
assignment; that appears to work.