The code that tries to turn off sysrq in rc.sysinit should read as follows:

# Turn off sysrq
if [ "$MAGIC_SYSRQ" = "no" -a -e /proc/sys/kernel/sysrq ]; then
        echo "0" > /proc/sys/kernel/sysrq
fi

The addition of "-a /proc/sys/kernel/sysrq" ensures that the script won't
try to disable sysrq if it isn't compiled into the current kernel.