screen brighness adjusts itself constantly

[Mathijs Veen]

As stated in title, screen brighness adjusts itself constantly: When adjusting brightness manualy, Galaxy Nexus device (maguro) is often dimmed immedeatly to some kind of default setting. (is there some kind of automatic brightness process at work, that overides the manual, but which has no interface? )
Usualy, this bug happens within seconds after the brightness is set manualy. Sometimes though, it happens later at (apparently) random moments. On rare occasions, it doesnt happen at all.
On every occasion however, the slider for manual setting stays where it is.

At first, I was thinking it was caused by an overzealous proximity sensor (which however works perfectly on android). Now I am leaning towards some sort of default setting or automated brightness. Judging from earlier posts on xde and LP, it seems there was such a feature at some stage in the beta.

content of media-info:
Ubuntu 13.10 - armhf (20131017)

mat@Lapbuntu:~$ adb shell getprop ro.cm.device
maguro

[Nicola Heald (notnownikki)]

Confirmed on nexus 7 as well