Backport 'six-days-to-eom' into 'glib-2-66'
Fix the 6-days-until-the-end-of-the-month bug
Closes #2215 (closed)
See merge request !1683 (merged)
(cherry picked from commit b5429b7e)
411aa464 Add a test for the 6-days-until-EOM bug da007790 Fix the 6-days-until-the-end-of-the-month bug