Fix bug in S_MOD

string.c

@@ -471,6 +471,7 @@ struct string *string_format(struct string *fmt, union vm_value arg)
 			parse_fmt_spec(&s, &spec);
 			append_fmt(&out, &spec, arg);
 			string_append_cstr(&out, s, strlen(s));
+			break;
 		}
 	}
 	return out;

test/Source/strings.jaf

@@ -72,6 +72,7 @@ void test_strings(void)
 	test_string("abc%Ddef % 42", "abc%Ddef" % 42, "abc４２def");
 	test_string("abc%4Ddef % 42", "abc%4Ddef" % 42, "abc　　４２def");
 	test_string("abc%04Ddef % 42", "abc%04Ddef" % 42, "abc００４２def");
+	test_string("\"%d %d\" % 42 % 43", "%d %d" % 42 % 43, "42 43");
 	// float
 	test_string("abc%fdef % 12.3", "abc%fdef" % 12.3, "abc12.300000def");
 	test_string("abc%.2fdef % 12.3", "abc%.2fdef" % 12.3, "abc12.30def");