fix #4546

Author: lperron

ortools/sat/cumulative_energy.cc

@@ -225,14 +225,15 @@ bool CumulativeEnergyConstraint::Propagate() {
 
       const int task_with_new_energy_max =
           start_event_task_time_[event_with_new_energy_max].task_index;
-      helper_->AddStartMinReason(task_with_new_energy_max, window_start);
-      helper_->AddEndMaxReason(task_with_new_energy_max, window_end);
-      if (!demands_->DecreaseEnergyMax(task_with_new_energy_max,
-                                       new_energy_max)) {
-        return false;
-      }
-
       if (helper_->IsPresent(task_with_new_energy_max)) {
+        helper_->AddPresenceReason(task_with_new_energy_max);
+        helper_->AddStartMinReason(task_with_new_energy_max, window_start);
+        helper_->AddEndMaxReason(task_with_new_energy_max, window_end);
+        if (!demands_->DecreaseEnergyMax(task_with_new_energy_max,
+                                         new_energy_max)) {
+          return false;
+        }
+
         theta_tree_.AddOrUpdateEvent(
             task_to_start_event_[task_with_new_energy_max],
             start_event_task_time_[event_with_new_energy_max].time *