Do not compute twice the children timesheets

review355001
(transplanted from 973bf618edb04399e9c86ba07054b455c7adb79f)

work.py

@@ -76,7 +76,7 @@ class Work(ModelSQL, ModelView):
                 ('parent', 'child_of', ids)
                 ], context=context)
         # force inactive ids to be in all_ids
-        all_ids = all_ids + ids
+        all_ids = list(set(all_ids + ids))
         clause = "SELECT work, sum(hours) FROM timesheet_line "\
                      "WHERE work IN (%s) "\
                      % ",".join(('%s',) * len(all_ids))