It seems like sourceforge has changed the download paths by using some mirrors and the file doesn't exist on the default gentoo place on: http://www.ibiblio.org/gentoo/distfiles/strace_4.4-1.tar.gz
I see the problem with the ebuild. Bug #2481 is going to deal with the problem in the long term.. A quick fix is to change the url download to telia.dl.sourceforge.net in the SRC_URI.