Backwards Compatibility for Cursed Inscriptions

[veryordinally]

Originally posted by @lgalabru in #2045 (comment)

We may have to add another rule, to get cursed inscription fully backward compatible: satoshis inscribed with a cursed inscription can be re-inscribed, with a cursed inscription (multiple times) or an inscription (only once).
There are many instances of satoshis that have been mis-inscribed in the past (inscription on 2nd input or whatever), and that were re-inscribed correctly later.
With your current spec, the satoshi would be bound to a cursed inscription with the first transaction, and the second, "legit" inscription would fail (because the satoshi is already bound to a cursed inscription). As a consequence, the inscription number sequence as we know it would break.

[veryordinally]

We encountered this issue when implementing #2145 - this is a tracking issue to document the solution we implemented to maintain backwards compatibility.