From Bugzilla Helper:
User-Agent: Mozilla/4.78 [en] (X11; U; Linux 2.4.16 i686; Nav)

Description of problem:
zsh links with /usr/lib/libcap, so it cannot be used in single
user mode when /usr is not yet mounted.  This is really annoying
if you make /bin/zsh root's shell, since you can't start a single
user mode shell.  Note that there may be additional issues with
zsh's loadable modules, as described below.

Version-Release number of selected component (if applicable):


How reproducible:
Always

Steps to Reproduce:
1. Enter single user mode
2. Make sure /usr is not mounted
3. Start zsh
	

Actual Results:  zsh didn't start

Expected Results:  zsh should have started

Additional info:

I'm not sure about the zsh 4.0.2 that RH is shipping, but 4.0.4
will use dynamically loaded modules.  This is an interesting
feature, but it will cause similar problems if the modules aren't
available if /usr isn't mounted.  I'd recommend configuring with
--disable-dynamic to avoid this (using modules appears to save
only about 200KB).  One expects that shells that are available 
from /bin will work in single user mode.