bug#47476: relative date of -1 month shows the wrong month

[Lars Noodén]

Severity: normal
Package: coreutils
Version: 8.32-4

On March 29, 2021, if a relative date of '-1 month' is passed to 'date',
then the output shows March instead of February.

$ date; date -d '-1 month'; date -d '1 month ago'; date -d 'last month';
Mon 29 Mar 2021 06:35:43 PM EEST
Mon 01 Mar 2021 05:35:43 PM EET
Mon 01 Mar 2021 05:35:43 PM EET
Mon 01 Mar 2021 05:35:43 PM EET

The output shows March when it clearly should show February instead.
This impairs the usefulness of the program a lot on certain days.