Post by Jim Meyering FYI: grep (due to its use of the new getprogname module) would fail to configure on OpenBSD 5.1. I'll soon push this to gnulib and then update grep's gnulib submodule to latest to pull it in.
Glad I tested on Fedora 25-to-be. The above caused program_invocation_short_name to always be the empty string. I fixed it by declaring __progname only in the narrow/later case in which it is required: