libvirt lts upgrade misses librbd dependency

Following the automated upgrade path from Precise to Trusty, libvirtd failed to load libvirt_driver_storage.so (and consequently libvirt_driver_qemu.so). In our case, this was fixed by installing librbd-dev (presumably due to librbd1 dependency).

Running "/etc/init.d/libvirt-bin restart" produced the following in libvirtd.log

LIBVIRTD.LOG
2014-11-05 09:47:29.359+0000: 5755: info : libvirt version: 1.2.2
2014-11-05 09:47:29.359+0000: 5755: error : virDriverLoadModule:79 : failed to load module /usr/lib/libvirt/connection-driver/libvirt_driver_storage.so /usr/lib/libvirt/connection-driver/libvirt_driver_storage.so: undefined symbol: rbd_create3
2014-11-05 09:47:29.365+0000: 5755: error : virDriverLoadModule:79 : failed to load module /usr/lib/libvirt/connection-driver/libvirt_driver_qemu.so /usr/lib/libvirt/connection-driver/libvirt_driver_qemu.so: undefined symbol: virStorageFileStat

The original version was the server install of Ubuntu 12.04. It has Zentyal installed, which manages most of the server features. The current version as given by lsb_release -rd:

OS VERSION:
Description: Ubuntu 14.04.1 LTS
Release: 14.04

LIBVIRT VERSION:
libvirt0 : 1.2.2-0ubuntu13.1.6

WHAT YOU EXPECTED TO HAPPEN:
a) Running "virsh list" would show active VMs
b) libvirt would load QEMU driver on start-up

WHAT HAPPENED INSTEAD:
a) Received error> error: no connection driver available for qemu:///system
b) libvirt loaded without QEMU driver - error only visible in /var/log/libvirtd/libvirtd.log (shown above)