Errors entering single-user mode; hang going back to multiuser

Several wrong-looking messages appear when entering single-user mode,
and when ^D is typed to exit the single-user shell, the system hangs trying to resume multi-user mode
(the graphical login never apperas, nor does the virtual-terminal login prompt).

I observed this testing with virtualbox. Haven't tried bare metal.

I will attach two screenshots, one showing the entry into single-user mode, the second showing the attempted exit.
But the bits which seemed relevant are reproduced below;

STEPS TO REPRODUCE:

1. Log in as root from a virtual console (in virtualbox: <host>-F1 and log in)
2. $ shutdown now # documented to enter single-user mode

/lib/init/init-d-script: 2: /etc/default/whoopsie: [General]: not found
...
ModemManager ... Caught signal, shutting down...
ModemManager ... Could not acquire the 'org.freedesktop.Modemmanger1' service name

3. When prompted, enter root password
...
4. ^D (or type 'exit')
...
/lib/init/init-d-script: 2: /etc/default/shoopsie: [General]: not found
systemd-logind: Failed to start user service: Unknown unit: user@108.service
systemd-logind: Failed to start user service: Unknown unit: user@0.service
systemd-logind: Failed to start user service: Unknown unit: user@1000.service
* Starting shoopsie shoopsie [fail]
(HANGS)

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: upstart 1.13.2-0ubuntu7
ProcVersionSignature: Ubuntu 3.18.0-11.12-generic 3.18.3
Uname: Linux 3.18.0-11-generic x86_64
ApportVersion: 2.15.1-0ubuntu4
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Jan 27 15:46:46 2015
InstallationDate: Installed on 2015-01-02 (25 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Alpha amd64 (20150102)
ProcKernelCmdline: BOOT_IMAGE=/boot/vmlinuz-3.18.0-11-generic root=UUID=96d674cd-12fb-4ad1-8d76-cffb545e6256 ro quiet splash vt.handoff=7
SourcePackage: upstart
UpgradeStatus: No upgrade log present (probably fresh install)
UpstartBugCategory: System
UpstartRunningSessionVersion: upstart 1.13.2
UpstartRunningSystemVersion: init (upstart 1.13.2)