[Asus UX31E] Ubuntu 14.10 fails to hibernate on empty battery

[mx80]

When the battery charge as reported by upower goes to 0 Wh the system should hibernate. It doesn't. Instead it keeps running, and eventually the machine powers down. At the time the charge reaches 0 Wh, the indicator in the notification area goes away (it reappears if I plug in the machine, let charge go above 0 Wh, then unplug again, but that's probably a separate bug in the indicator?).

Happens only when set to hibernate on critically low battery; if set to shut down, it does.

Happens with both the 3.16.0-23 kernel and the upstream 3.17.1 kernel. Has happened in the past on previous distributions as well, but the UX31E suffered from other power issues where it randomly turned off even when the battery wasn't low, so never managed to reproduce it consistently. Power measurement, notifications of low and critical charge, etc. now work, and it even powers down on critical battery, but it just doesn't hibernate. Hibernation itself works fine with pm-hibernate and also with

dbus-send --print-reply --system --dest=org.freedesktop.UPower /org/freedesktop/UPower org.freedesktop.UPower.Hibernate

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: gnome-power-manager 3.8.2-1ubuntu2
Uname: Linux 3.17.1-031701-generic x86_64
ApportVersion: 2.14.7-0ubuntu8
Architecture: amd64
CurrentDesktop: Unity
Date: Sat Oct 25 22:22:14 2014
InstallationDate: Installed on 2012-05-01 (907 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Beta amd64 (20120328)
SourcePackage: gnome-power-manager
UpgradeStatus: Upgraded to utopic on 2014-10-25 (0 days ago)
---
ApportVersion: 2.14.7-0ubuntu8
Architecture: amd64
CurrentDesktop: Unity
DistroRelease: Ubuntu 14.10
InstallationDate: Installed on 2012-05-01 (907 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Beta amd64 (20120328)
Package: gnome-power-manager 3.8.2-1ubuntu2
PackageArchitecture: amd64
Tags: utopic
Uname: Linux 3.17.1-031701-generic x86_64
UpgradeStatus: Upgraded to utopic on 2014-10-25 (0 days ago)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True