make sure that the precision is not the empty string

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@14773 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Form/FormulatorPatch.py

@@ -1141,7 +1141,7 @@ class FloatWidget(TextWidget):
       """
       input_style = field.get_value('input_style')
       precision = field.get_value('precision')      
-      if precision != 0:
+      if precision not in (None, '') and precision != 0:
         for x in xrange(1, precision):
           input_style += '5'
       else: