Extend the extended syntax for month day sets (!89) · Merge requests · Libraries / KOpeningHours

2021 Dec 26-28,Dec 30-31 was being simplified to 2021 Dec 26-28,30-31 which then couldn't be parsed back. The unofficial grammar at https://wiki.openstreetmap.org/wiki/Key:opening_hours does support this:

daily: months [   monthdays [ , monthdays ]... ]
months: Mth [ -Mth ]
monthdays: dd [ -dd ]

Extend the extended syntax for month day sets