Is this a bug for zsh 4.2.3?

[Paul Lew <paullew@xxxxxxxxx>]

Just upgrade our zsh from 4.2.1 to 4.2.3 for both our solaris and
Linux platforms.  If I cd to a directory that is mounted over the
network, then futher sub shell started will exit prematurally in the
middle of my .zshrc.  I finally was about to provide the simplest case
with only 4 lines in my .zshenv file and no .zshrc file:

	> cat .zshenv
	echo ok 1
	path=(/bin /usr/bin)
	[[ $HOME/.zshrc -nt .zshrc ]] || echo ok 2
	echo ok 3

If I start zsh from $HOME, then everything is ok:

	> cd $HOME
	> zsh
	ok 1
	ok 2
	ok 3
	cns-build4% exit

However, if I cd to a network mounted directory and then start the
zsh, the zsh will ignore the rest of the .zshenv from the line with
-nt comparison.

	> cd /auto/insbu-cnstools/dist
	> zsh
	ok 1
	cns-build4%

However, if I changed the line with -nt comparison to:

    [[ $HOME/.zshrc -nt $HOME/.zshrc ]] || echo ok 2

Then I got the rest of script executed.  What's going on here?
Any idea?  TIA.