Odd user/group identity lookup problem

I'm building F18 images with livecd-creator on F18 and for the first build 
attempt after boot, I see many unexpected errors like this snippet shows:

[snip]
  Installing: libsemanage                  ##################### [315/492] 

  Installing: shadow-utils                 ##################### [316/492] 

groupadd: failure while writing changes to /etc/group
groupadd: failure while writing changes to /etc/group
  Installing: libutempter                  ### [317/492]warning: group 
utempter does not exist - using root
warning: group utmp does not exist - using root
  Installing: libutempter                  ##################### [317/492] 

[snip]
  Installing: parted                       ##################### [331/492] 

groupadd: failure while writing changes to /etc/group
useradd: group 'dhcpd' does not exist
  Installing: dhcp                         #################### 
[332/492]warning: user dhcpd does not exist - using root
warning: group dhcpd does not exist - using root
warning: user dhcpd does not exist - using root
warning: group dhcpd does not exist - using root
warning: user dhcpd does not exist - using root
warning: group dhcpd does not exist - using root
  Installing: dhcp                         ##################### [332/492] 

[snip]
  Installing: os-prober                    ##################### [335/492] 

groupadd: failure while writing changes to /etc/group
  Installing: openssh                      ########## [336/492]warning: 
group ssh_keys does not exist - using root
[snip]
  Installing: samba-common                 ##################### [338/492] 

Failed to initialize SELinux context: No such file or directory
  Installing: iputils                      ##################### [339/492] 

[snip]
  Installing: mesa-dri-drivers             ##################### [347/492] 

groupadd: failure while writing changes to /etc/group
useradd: group 'polkitd' does not exist
  Installing: polkit [348/492]warning: user polkitd does not exist - using 
root
[snip]
  Installing: alsa-utils                   ##################### [354/492] 

error: %pre(rpcbind-0.2.0-17.fc18.i686) scriptlet failed, exit status 6
error: rpcbind-0.2.0-17.fc18.i686: install failed
groupadd: failure while writing changes to /etc/group
useradd: group 'chrony' does not exist
  Installing: chrony [356/492]warning: group chrony does not exist - using 
root
  Installing: chrony                       #################### 
[356/492]warning: user chrony does not exist - using root
warning: group chrony does not exist - using root
warning: user chrony does not exist - using root
warning: group chrony does not exist - using root
  Installing: chrony                       ##################### [356/492] 

[snip]

If I let it run through to completion and rerun the exact same command 
again, everything works normally.  I used to see this behavior for every 
build attempt prior to sssd coming along when I was still using nscd, if 
nscd was running.  Back then I'd have to stop nscd for the duration of the 
build.  I never had such a problem with sssd, but this looks eerily 
familiar now with F18 (where I'm still using sssd instead of nscd).

Has anyone else seen something similar, or is this a known bug?  I have 
not had a chance to dig into this yet, but I've been seeing this with F18 
since before Alpha was out.

PS.  FWIW, this F18 box started life as F17 and was been yum distro-sync'd 
and kept updated.

--
John Florian