Obtain a cell even when a cell is passed if this cell is None.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@1433 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Form/Form.py

@@ -85,7 +85,7 @@ class ERP5Field(Field):
             # This allows to pass some pointer to the local object
             # through the REQUEST parameter. Not very clean.
             # Used by ListBox to render different items in a list
-            if kw.has_key('REQUEST') and not kw.has_key('cell'): kw['cell'] = kw['REQUEST']
+            if kw.has_key('REQUEST') and not kw.get('cell'): kw['cell'] = kw['REQUEST']
             try:
               value = tales_expr.__of__(self)(**kw)
             except: