Comment 1 for bug 1431650

The work-around in use:

  Remove the multipath udev rules from the initramfs.
  Note: this doesn't remove multipath support from it; there's more in there.
            Boot from multipath devices works normally (and faster :-)

 $ grep 'for rules in' /usr/share/initramfs-tools/hooks/multipath
   for rules in 95-multipath.rules; do

 $ sudo sed '/for rules in/ s:95-multipath.rules::' -i /usr/share/initramfs-tools/hooks/multipath

 $ grep 'for rules in' /usr/share/initramfs-tools/hooks/multipath
   for rules in ; do

 $ sudo update-initramfs -u
 update-initramfs: Generating /boot/initrd.img-3.19.0-7-generic

 $ sudo reboot