You're receiving this bug because the package in Summary has produced _FORTIFY_SOURCE related warnings indicating the presence of a sure overflow in a static buffer.
Even though this is not always an indication of a security problem it might even be. So please check this out ASAP.
By the way, _FORTIFY_SOURCE is disabled when you disable optimisation, so don't try finding out the cause using -O0.
Your friendly neighborhood tinderboxer
Created attachment 247527 [details]
+*acpitool-0.5.1-r1 (30 Jan 2012)
+ 30 Jan 2012; Samuli Suominen <firstname.lastname@example.org>
+ +acpitool-0.5.1-r1.ebuild, +files/acpitool-0.5.1-ac_adapter.patch,
+ +files/acpitool-0.5.1-battery.patch, +files/acpitool-0.5.1-kernel3.patch,
+ Fix compability with Linux 3.x wrt #377355 by Damien Thébault. Fix reading
+ of values from ac_adapters and batteries. Rewrite part of the wakeup code.
+ This will also close #337565 (overflow revealed by _FORTIFY_SOURCE) by Diego
+ Elio Pettenò.
(As it appears, the Debian maintainer fixed this "while at it" in their patchset)