It adds support for metadata fetcher hooks, and the lister_name and lister_instance_name
parameter to the constructor (and we need loaders to accept these params before
swh-scheduler 1.1.0 starts sending the params)
Plan:
- [ ] Deploy loader.{core,cvs,git,svn,bzr,mercurial}.
- [ ] Restart impacted services swh-worker@loader_{vcs} for vcs in ...
- [ ] Might as well restart the machines directly...