Why does Java 8 DateTimeFormatter allows an incorrect month value in ResolverStyle.STRICT mode?

Question

Why does this test pass, while the month value is obviously invalid (13)?

@Test
public void test() {

    String format = "uuuuMM";

    String value = "201713";

     DateTimeFormatter.ofPattern(format).withResolverStyle(ResolverStyle.STRICT)
        .parse(value);

}

When using a temporal query, the expected DateTimeParseException is thrown:

DateTimeFormatter.ofPattern(format).withResolverStyle(ResolverStyle.STRICT)
    .parse(value, YearMonth::from);

What happens when no TemporalQuery is specified?

---

EDIT: the 13 value seems to be a special one, as I learned thanks to the answer of ΦXocę 웃 Пepeúpa ツ (see Undecimber).

But the exception is not thrown even with another value, like 50:

@Test
public void test() {

    String format = "uuuuMM";

    String value = "201750";

     DateTimeFormatter.ofPattern(format).withResolverStyle(ResolverStyle.STRICT)
        .parse(value);

}