Do not retry failing cron task directly

The next call datetime is set even if the task is failing. This way it will be
retried based on the configured frequency.

issue10695
review358751002
(grafted from befd1119ab8d12bf79e2b439376940f251b03280)

--HG--
branch : 6.0

trytond/ir/cron.py

@@ -162,8 +162,6 @@ class Cron(DeactivableMixin, ModelSQL, ModelView):
                     try:
                         with processing(name):
                             cron.run_once()
-                            cron.next_call = cron.compute_next_call(now)
-                            cron.save()
                             transaction.commit()
                     except Exception as e:
                         transaction.rollback()
@@ -171,6 +169,9 @@ class Cron(DeactivableMixin, ModelSQL, ModelView):
                                 and count):
                             continue
                         logger.error('%s failed', name, exc_info=True)
+                    cron.next_call = cron.compute_next_call(now)
+                    cron.save()
+                    transaction.commit()
                     break
         while transaction.tasks:
             task_id = transaction.tasks.pop()