CallsBestMatchView is not updated properly when a contact's phone number is changed in Contacts

Changing a matching contact's phone number in Contacts makes the best match disappear:

** (sm.puri.Calls:3397): DEBUG: 14:10:12.537: Best match property notified
** (sm.puri.Calls:3397): DEBUG: 14:10:12.541:  Best match disappeared

However, changing the phone number back again does not make the match reappear.

This may be a bug in libfolks.