Comment 93 for bug 1073433

The original description does not mention removing of network-manager
and other packages.

The phrase concerning redundant open files in unclear for me.
Is there any files open for writing? I wonder if the problem
if the debug scripts is removed.

Instead of plymouth removing, the splash screen can be suppressed
by setting empty
GRUB_CMDLINE_LINUX_DEFAULT=""
in /etc/default/grub
(remove default options "quiet" and "splash")
and run
sudo update-grub

/etc/default/halt can be temporally changed to
HALT=halt
this will allow to inspect very last messages during shutdown.

VERBOSE=yes
in /etc/default/rcS will add a couple more messages.

Finally
sudo initctl log-priority info
sudo sysctl kernel.printk="7 4 1 7"
before shutdown makes upstart quite verbose.