Third, I don't know for sure if pkg_install actually needs curses, or whether the check that's included in its autoconf script is simply vestigial. The bootstrap error I originally reported pertained to tnftp (originally its configure script didn't warn about not finding curses either). I submitted the PR with the fix for pkg_install under the assumption its existing check (silent in the case of failure) was indeed relevant.
pkg_install/lib/ftpio.c has the function ftp_start() which makes use of termcap functionality. So it looks like its autoconf reference isn't vestigial. Regards, Dave