In the deposit, the swh_anchor_id is in the new format:
swh:1:dir:<hash>;?origin=<origin>;visit=<snp-hash>;...
When, previously in the format:
swh:1:dir:<hash>;?origin=<origin>
This adapts the extraction to take into account the new format and provides the
end bound the data.slice call.
This is kind of fragile, as it assumes that the visit qualifiers will appear immediately after the origin qualifier.
It would be better to do something like: