Do not include start date when searching previous fiscalyear to cumulate

As there is a check to ensure that fiscalyears does not overlap it does not
make sense to include fiscalyears which end on the same start date as the
start of the current fiscalyear.

issue5131
review41811002

account.py

@@ -829,7 +829,7 @@ class Account(ModelSQL, ModelView):
         fiscalyear = None
         if youngest_fiscalyear:
             fiscalyears = FiscalYear.search([
-                    ('end_date', '<=', youngest_fiscalyear.start_date),
+                    ('end_date', '<', youngest_fiscalyear.start_date),
                     ('company', '=', youngest_fiscalyear.company),
                     ], order=[('end_date', 'DESC')], limit=1)
             if fiscalyears: