Starring doesn't work for non indexed directories
Right now if trying to star a file it doesn't work in non indexed directories, since we use Tracker for it.
There isn't a good solution for this, since we require files to be indexed, and indexing is an idle operation so we cannot wait for that to star a file. We will need either more collaboration from Tracker, or a different solution.
For now, we will star files only in XDG folders, which are indexed by default. However, the user can change this and we don't take it into account right now, so this need a better solution for Nautilus 3.30. Another solution would be to query as part of the NautilusFile cache the tracker information.