rev-list: --left/right-only are mutually exclusive

Signed-off-by: NJunio C Hamano <gitster@pobox.com>

revision.c

@@ -1284,8 +1284,12 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 	} else if (!strcmp(arg, "--left-right")) {
 		revs->left_right = 1;
 	} else if (!strcmp(arg, "--left-only")) {
+		if (revs->right_only)
+			die("--left-only is incompatible with --right-only");
 		revs->left_only = 1;
 	} else if (!strcmp(arg, "--right-only")) {
+		if (revs->left_only)
+			die("--right-only is incompatible with --left-only");
 		revs->right_only = 1;
 	} else if (!strcmp(arg, "--count")) {
 		revs->count = 1;