>=dev-libs/boost-1.49.0-r1 now have empty src_test(), but src_install() still contains code related to src_test(). status/regress.log was created in src_test(): http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/dev-libs/boost/boost-1.49.0-r1.ebuild?revision=1.10&view=markup#l568
Created attachment 328614 [details, diff] boost.patch Patch backported from Progress Overlay.