[Feisty] upstart fails to enter runleve 1 when 1 is set in boot parameter

[Steven Shiau]

Binary package hint: upstart

upstart supposed to be 100% compatible with old sysv-rc init. However, in Feisty, the upstart version 0.3.8-1 can not enter runleve 1 when 1 is set in boot parameter.
Steps to reproduce:
1. Boot Feisty
2. When grub boot menu is shown, press Esc
3. Press "e" to edit, append "1" in kernel boot parameter

Results:
1. Feisty still enters runlevel 2.
2. cat /proc/cmdline, the "1" is shown in /proc/cmdline.

In /etc/event.d/rc-default, the line should not only parse "-s" "single" "S", but also 0-6 should be parsed:
if grep -q -w -- "-s\|single\|S" /proc/cmdline; then