[FIX] fields: when executing (4, *) operations on o2m fields, check the existence...

If the o2m field linked to the o2m is stored on a different table (eg: model with _inherit), previous request would crash as the field do not exists in the '_table' sql table

bzr revid: mat@openerp.com-20140327111241-klftr0s8v8i68nxp

diff --cc openerp/osv/fields.py
index 1ef47bc,986fd49..17e6147
--- 1/openerp/osv/fields.py
--- 2/openerp/osv/fields.py
+++ b/openerp/osv/fields.py
@@@ -571,7 -571,9 +571,10 @@@ class one2many(_column)
                  else:
                      cr.execute('update '+_table+' set '+self._fields_id+'=null where id=%s', (act[1],))
              elif act[0] == 4:
-                 cr.execute("select 1 from {0} where id=%s and {1}=%s".format(_table, self._fields_id), (act[1], id))
++                # table of the field (parent_model in case of inherit)
+                 field_model = self._fields_id in obj.pool[self._obj]._columns and self._obj or obj.pool[self._obj]._all_columns[self._fields_id].parent_model
+                 field_table = obj.pool[field_model]._table
+                 cr.execute("select 1 from {0} where id=%s and {1}=%s".format(field_table, self._fields_id), (act[1], id))
                  if not cr.fetchone():
                      # Must use write() to recompute parent_store structure if needed and check access rules
                      obj.write(cr, user, [act[1]], {self._fields_id:id}, context=context or {})