forkless-exec failure on dgux

[Roderick Schertler <roderick@xxxxxxxx>]

Using 3.0.3-test4 this command

    zsh -fc ': | /bin/echo ok'

fails for me about 90% of the time.  The race is somehow related to the
first command in the pipeline being built in and the second being
external and execed without a fork.  The failure doesn't happen if the
first command is external or the second is a builtin or if there's
another command after this pipeline.

    $ ./zsh -fc ': | /bin/echo ok'
    zsh: segmentation fault  ./zsh -fc : | /bin/echo ok

    $ ./zsh -fc ': | echo ok'
    ok

    $ ./zsh -fc ': | /bin/echo ok; true'
    ok

    $ ./zsh -fc '/bin/echo foo | /bin/echo ok'
    ok

Unfortunately I don't get this on both of the OSs I've got available, I
only get it on dgux.  Is there some info I can pull out of the debugger
which might help someone know what is going wrong here?  I've started
trying to debug it myself, but it isn't going well.

As a workaround I thought to force last1 to be 0 at the top of
execpline().  This caused this command (part of /etc/zprofile)

    exec 3>&1

to trigger this warning, though,

    /etc/zprofile: redirection with no command [204]

so I guess that wasn't such a great idea after all.  Can anyone offer a
proper workaround I could install temporarily?

-- 
Roderick Schertler
roderick@xxxxxxxx