Comment 2 for bug 886439

verified per original reporter's instructions:

$ apt-cache policy upstart
upstart:
  Installed: 1.3-0ubuntu10
  Candidate: 1.3-0ubuntu11
  Version table:
     1.3-0ubuntu11 0
        500 http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ oneiric-updates/main amd64 Packages
 *** 1.3-0ubuntu10 0
        500 http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ oneiric/main amd64 Packages
        100 /var/lib/dpkg/status
$ sudo lsof > lsof.out.pre
$ sudo apt-get install upstart
...
Setting up upstart (1.3-0ubuntu11) ...
Installing new version of config file /etc/init/failsafe.conf ...
$ sudo lsof > lsof.out.post
$ sudo reboot

I'll attach lsof.out.post, lsof.out.pre, and a console log showing the 'mount: / is busy' and subsequent check on reboot.