Prevent infinite loop.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@25501 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/PeriodicityLine.py

@@ -102,5 +102,11 @@ class PeriodicityLine(Path, PeriodicityLineMixin):
     while next_start_date <= to_date:
       result.append((next_start_date,
                      self.getPeriodicityTermStopDate(next_start_date)))
-      next_start_date = self.getNextPeriodicalDate(next_start_date)
+      
+      new_next_start_date = self.getNextPeriodicalDate(next_start_date)
+      if new_next_start_date==next_start_date:
+        # prevent infinite loop.
+        break
+      else:
+        next_start_date = new_next_start_date
     return result