Comment 8 for bug 588060

Ok, so here is what happens:
import deletes the content (not file ids) of everything.
Then it adds all the content again.
Then it selects the file ids to use for things that were not readded.

This is pretty clever, but not helpful for renames.

I've made the file id look up happen earlier, and it accurately handles the rename + add case I'm facing. You might like to try my branch.