TEXT(?t) broken and E2E Tests didn't catch it

[niklas88]

I just noticed that the TEXT(?t) for a text query like (on scientists):

SELECT ?x SCORE(?t) TEXT(?t) WHERE {
  ?x <is-a> <Scientist> .
  ?x <Place_of_birth> <Ulm> .
  ?t ql:contains-entity ?x .
  ?t ql:contains-word "relati*"
}
ORDER BY DESC(SCORE(?t))

is broken as it shows the wrong snippets. On Wikidata + Wikipedia I also get unexpectedly empty results with TextOperationWithFilter for example for the "Astronauts who walked on the moon" text query example (which is also not used in the E2E Tests) but TextOperationWithoutFiler at least yields results. Even weirder running the current version on our existing Clueweb + Freebase index crashes on text operations.

I've used git bisect to identify a6b4775 as the first commit where the TEXT(?t) failure on scientists occurs. Reverting that commit on master results in a working "Astronauts who walked on the moon" text query with the Wikipedia + Wikidata index but only when the ?time_in_space part is removed, which triggers TextOperationWithoutFilter to be used. So it looks like TextOperationWithFilter is separately broken though subtly as it seems to work on Scientists (it is used in the above query).

That said worse than the bug itself is that the E2E tests don't care at all about the TEXT(?t) content and that TextOperationWithFilter is not triggered by any of those queries (though as I said I couldn't yet trigger the problem seen on Wikipedia+Wikidata on Scientist).