bitbake package-index no longer works. In fact, the do_build() step (which is where all the work happens) doesn't even seem to be called. A workaround is to build some image with a root file system that forces the package databases to be updated, but this is very clunky overkill.
Fixed in http://git.pokylinux.org/cgit.cgi/poky-contrib/commit/?h=tk/master&id=9a3f25dfb7c0cf797e61f19e23583f2037250c63