svn: Add missing coverage on svn implementation
It appears SvnLoaderFromDumpArchive is missing actual tests (without mock). That needs fixing.
As some recent tryout to try and instantiate revealed difficult. That serves both the purpose to avoid:
- code rot
- document usage
That does not exclude the fact that the loader needs a better documentation as well.
Migrated from T3686 (view on Phabricator)