Build log should always be verbose as per talk on dev-ML, please force it until some EAPI includes a fix for this. Other versions might be affected as well.
Created attachment 320372 [details] xorg-server-1.12.2:20120623-204131.log.xz
obsolete by http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=1cc39de72ac5311db748341ef9183586556719d9