do not allow breaks of 0 time

dream/simulation/ShiftScheduler.py

@@ -128,7 +128,7 @@ class ShiftScheduler(ObjectInterruption):
                     # sometimes the time to end the last process may overcome the time to restart theshift
                     # so off-shift should not happen at such a case
                     if len(self.remainingShiftPattern)>1:
-                        if self.env.now>self.remainingShiftPattern[1][0]:
+                        if self.env.now>=self.remainingShiftPattern[1][0]:
                             self.remainingShiftPattern.pop(0)                
                             # if there is no more shift data break the loop
                             if len(self.remainingShiftPattern)==0: