QDate returns wrong week number for last 4 days of 2020

QDate(2020, 12, 31).weekNumber() returns "1" while it should return "53".

The 31st December 2020 is on Thursday, according to [1] - "If 31 December is on a Monday, Tuesday or Wednesday, it is in week 01 of the next year. If it is on a Thursday, it is in week 53 of the year just ending".

Furthermore, QDate(2021, 1, 1).weekNumber() (the next day) actually returns "53", which is correct. See below.

[1] - https://en.wikipedia.org/wiki/ISO_week_date#Last_week

—

Attached is a simple test case which outputs the QDate week number of the last week in year 2020, here's the output:

(390) main: Week for QDate("2020-12-26") is 52
(390) main: Week for QDate("2020-12-27") is 52
(390) main: Week for QDate("2020-12-28") is 1
(390) main: Week for QDate("2020-12-29") is 1
(390) main: Week for QDate("2020-12-30") is 1
(390) main: Week for QDate("2020-12-31") is 1
(390) main: Week for QDate("2021-01-01") is 53
(390) main: Week for QDate("2021-01-02") is 53
(390) main: Week for QDate("2021-01-03") is 53
(390) main: Week for QDate("2021-01-04") is 1
(390) main: Week for QDate("2021-01-05") is 1