merge: simplify ff-only option

No functional changes.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/merge.c

@@ -186,13 +186,6 @@ static int option_parse_n(const struct option *opt,
 	return 0;
 }
 
-static int option_parse_ff_only(const struct option *opt,
-			  const char *arg, int unset)
-{
-	fast_forward = FF_ONLY;
-	return 0;
-}
-
 static struct option builtin_merge_options[] = {
 	{ OPTION_CALLBACK, 'n', NULL, NULL, NULL,
 		N_("do not show a diffstat at the end of the merge"),
@@ -210,9 +203,9 @@ static struct option builtin_merge_options[] = {
 	OPT_BOOL('e', "edit", &option_edit,
 		N_("edit message before committing")),
 	OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
-	{ OPTION_CALLBACK, 0, "ff-only", NULL, NULL,
+	{ OPTION_SET_INT, 0, "ff-only", &fast_forward, NULL,
 		N_("abort if fast-forward is not possible"),
-		PARSE_OPT_NOARG | PARSE_OPT_NONEG, option_parse_ff_only },
+		PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, FF_ONLY },
 	OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
 	OPT_BOOL(0, "verify-signatures", &verify_signatures,
 		N_("Verify that the named commit has a valid GPG signature")),