In the linux-2.6.0 test series, when swapping is not explicitly enabled, the 
user sees an error message from awk, as it cannot open /proc/swaps

The code in /etc/rc.d/init.d/halt goes:

# Turn off swap, then unmount file systems.
SWAPS=`awk '! /^Filename/ { print $1 }' /proc/swaps`
[ -n "$SWAPS" ] && runcmd $"Turning off swap: " swapoff $SWAPS

This is fixed by:

[ -f /proc/swaps ] && SWAPS=`awk '! /^Filename/ { print $1 }' /proc/swaps`

And so, is a very cheap fix.