fix typo

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@17241 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/DateUtils.py

@@ -230,7 +230,7 @@ def getRoundedMonthBetween(from_date=None, to_date=None, rounded_day=False):
     from math import ceil
     interval_day = ceil(to_date - from_date)
   else:
-    interval_day = to_date - from_dat
+    interval_day = to_date - from_date
   if interval_day >= days_in_month / 2.:
     return_value += 1
   return return_value