Battery left reported in percentage instead of time on Lucid w/ natty backport kernel

Release: 10.04
Codename: lucid
upower 0.9.1-1
kernel 2.6.38-10-generic

On a Lucid laptop, with the linux-image-generic-lts-backport-natty kernel installed, upower reports remaining battery charge in percentage rather than in time. This happens because some time between 2.6.32 and 2.6.38, the kernel replaced the current_now sysfs attribute with a new power_now attribute, and this information is required to determinate current utilization so that upower can compute time remaining.

See also http://<email address hidden>/msg00946.html.

Steps to reproduce:

1. Take a standard Lucid laptop install. In my case, I've reproduced this on a Thinkpad X200 and a Thinkpad X220, but I'm sure it affects many models.
2. Notice that the gnome battery applet reports battery time remaining in hours and minutes when AC is unplugged.
3. Install linux-image-generic-lts-backport-natty and reboot.
4. Notice that now the gnome battery applet reports percentage of battery remaining instead of time.

I'm attaching a patch against Lucid's upower 0.9.1 that fixes this. It integrates the upstream fix from http://cgit.freedesktop.org/upower/commit/?id=2af7a6e091bb62faff9cdda5bb7e3fb5dcc8d15a .