multi-pack-index: simplify handling of unknown --options

Although parse_options() can handle unknown --options just fine, none
of 'git multi-pack-index's subcommands rely on it, but do it on their
own: they invoke parse_options() with the PARSE_OPT_KEEP_UNKNOWN flag,
then check whether there are any unparsed arguments left, and print
usage and quit if necessary.

Drop that PARSE_OPT_KEEP_UNKNOWN flag to let parse_options() handle
unknown options instead, which has the additional benefit that it
prints not only the usage but an "error: unknown option `foo'" message
as well.

Do leave the unparsed arguments check to catch any unexpected
non-option arguments, though, e.g. 'git multi-pack-index write foo'.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/multi-pack-index.c

@@ -134,7 +134,7 @@ static int cmd_multi_pack_index_write(int argc, const char **argv)
 		opts.flags |= MIDX_PROGRESS;
 	argc = parse_options(argc, argv, NULL,
 			     options, builtin_multi_pack_index_write_usage,
-			     PARSE_OPT_KEEP_UNKNOWN);
+			     0);
 	if (argc)
 		usage_with_options(builtin_multi_pack_index_write_usage,
 				   options);
@@ -176,7 +176,7 @@ static int cmd_multi_pack_index_verify(int argc, const char **argv)
 		opts.flags |= MIDX_PROGRESS;
 	argc = parse_options(argc, argv, NULL,
 			     options, builtin_multi_pack_index_verify_usage,
-			     PARSE_OPT_KEEP_UNKNOWN);
+			     0);
 	if (argc)
 		usage_with_options(builtin_multi_pack_index_verify_usage,
 				   options);
@@ -202,7 +202,7 @@ static int cmd_multi_pack_index_expire(int argc, const char **argv)
 		opts.flags |= MIDX_PROGRESS;
 	argc = parse_options(argc, argv, NULL,
 			     options, builtin_multi_pack_index_expire_usage,
-			     PARSE_OPT_KEEP_UNKNOWN);
+			     0);
 	if (argc)
 		usage_with_options(builtin_multi_pack_index_expire_usage,
 				   options);
@@ -232,7 +232,7 @@ static int cmd_multi_pack_index_repack(int argc, const char **argv)
 	argc = parse_options(argc, argv, NULL,
 			     options,
 			     builtin_multi_pack_index_repack_usage,
-			     PARSE_OPT_KEEP_UNKNOWN);
+			     0);
 	if (argc)
 		usage_with_options(builtin_multi_pack_index_repack_usage,
 				   options);