Merge Case does not transfer custom case fields to new copy of case

If a contact w/ case(s) is merged into another contact, the original case is 'resolved' (on the duplicate contact) and a new copy is created and linked to the main contact. Merge is handled this way for cases due to the business rule that an audit trail must be available for all changes to cases and case activities.

However, the new case copy is missing any case custom fields from the original case.

– original post —
If you have Case with custom fields having activity(ies) also with custom fields and perform reassign case,
custom fields are not created in the new case - nor custom fields of activities in the case.

Quite showstopper for custom business logic.