check if property doesn't already exists

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@9703 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Banking/tests/TestERP5BankingMixin.py

@@ -565,7 +565,10 @@ class TestERP5BankingMixin:
     # the erp5 site
     self.portal = self.getPortal()
     # the default currency for the site
+    if not self.portal.hasProperty():
       self.portal.manage_addProperty('reference_currency_id', 'EUR', type='string')
+    else:
+      self.portal.edit(reference_currency_id="EUR")
     # the person module
     self.person_module = self.getPersonModule()
     # the organisation module