This simplifies the base classes indirection introduced to make the tests run.
It keeps the unittest scaffolding to allow declaring tests once and reuse
amongst the different loader instances (GitLoader, GitLoaderFromDisk,
This uses the pg-storage and no longer the in-memory storage.
The code coverage increased from 82% to 85%.
This duplicates a bit helper function from the loader-core (equivalent code
exists in loader-svn). I'll attend to this to remove that duplication soon.
Related to T2482