Taking a look at emacs trunk http://bzr.savannah.gnu.org/lh/emacs/trunk/files there is no configure.in, therefore emacs-vcs doesn't build because sed doesn't find the file (line 96 and others in the ebuild) Reproducible: Always Actual Results: Emacs-vcs doesn't compile
The file (configure.in) has been renamed configure.ac http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=6e5a5dcf6b10dd2cef22ed95fd995fc88b8a3fba
Fixed on 07/14/2012 by Ulrich Müller