Some binary packages require libtinfo.so.5 which is not provided by app-emulation/emul-linux-x86-baselibs. It would be helpful if ncurses was compiled with the tinfo USE flag enabled so that this library would be provided for these packages. At this time the only workaround is to create a symlink pointing to libncurses.so.5.
Lots of other packages fail when sys-libs/ncurses is built with USE=tinfo, since they expect certain symbols to be exposed by libncurses and not libtinfo, so we have a long way to go before this can be safely done. The tracker bug in question is probably incomplete as of now and even the remaining bugs will take some time to fix.