This reverts commit 5cda0ca626010cccc7e7f3f73fbfb1b20702ac40 (D7907) which is not the proper
fix.
The proper fix plan becomes:
- fix documentation to explicit the get_current_version intention
- either fix swh-scrubber (and whatever else non-compliants backends) or provide a
default implementation in BaseDb [1] to actually expose that get_current_version (that
can then be overriden if something specific needs to be developed for a new
datastore).
[1] does both by updating swh.core.db