Merge branch 'ef/non-ascii-parse-options-error-diag' into maint

* ef/non-ascii-parse-options-error-diag:
  parse-options: report uncorrupted multi-byte options

parse-options.c

@@ -471,8 +471,11 @@ int parse_options(int argc, const char **argv, const char *prefix,
 	default: /* PARSE_OPT_UNKNOWN */
 		if (ctx.argv[0][1] == '-') {
 			error("unknown option `%s'", ctx.argv[0] + 2);
-		} else {
+		} else if (isascii(*ctx.opt)) {
 			error("unknown switch `%c'", *ctx.opt);
+		} else {
+			error("unknown non-ascii option in string: `%s'",
+			      ctx.argv[0]);
 		}
 		usage_with_options(usagestr, options);
 	}