If I run, for example, `locale -k nonexistant`, I get a helpful error message: `Unknown keyword: 'nonexistant'`.
However, `locale` in this case still exits with an exit code of 0. It should probably exit with nonzero instead to indicate the failure in finding the keyword.
An identical bug also exists in NetBSD. See https://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=54692