If you edit a task to associate it with project Foo at the same time as someone else and get in just after them, or if you didn't notice it was there already, you get the following error:
> The action you are taking has no effect:
>
> * Edges already exist; transaction has no effect.
Maybe it should just say "This task is already associated with this project."? (I imagine that this is a generic error for multiple cases where the graph is being populated, so this might be a bigger request than just an i18n tweak.)