fix final match not visible

tournaments/models/tournament.py

@@ -81,7 +81,7 @@ class Tournament(models.Model):
         for team_registration in self.teamregistration_set.all():
             if team_registration.is_valid_for_summon():
                 next_match = team_registration.next_match()
-                if next_match:
+                if next_match and next_match.start_date is not None:
                     names = team_registration.team_names()
                     stage = next_match.summon_stage_name()
                     weight = team_registration.weight