Produits Entr'ouvert » Calebasse

There may be no current state, we have to handle it (fixes #4532).

Commit 09970a47d3528562940bb42ae7ce9b7904c44c62 introduced a more accurate
    way to get a Patient record status at a given date returning None if there is
    no state rather returning the last state not applying to the date given.

Then a current state may be None if the states are only applying in the future.
    So we have to handle that case.