unicode-2 branch segfaulting on MacOS X?

[Geoffrey Alan Washburn]

I've been trying to get the latest revision of the emacs-unicode-2 
branch to build and run under MacOS X.  Building seems to work fine, 
I've been using the following configuration

./configure --prefix=/local --enable-font-backend --with-gtk --with-xft 
--with-tiff --with-ungif --with-xpm --enable-asserts CPPFLAGS=-idirafter 
/usr/X11R6/include

However, when I attempt to invoke emacs with

emacs --enable-font-backend --font "Bitstream Vera Sans Mono-16"

it seems to be segfaulting somewhere in font_unparse_fcname.  Any ideas?