[7.0] Write 0 in field many2one when value is False

[Luis Ernesto García Medina - http://www.vauxoo.com]

1) Steps to reproduce the issue you have observed
use write function in a module, to set null in field many2one used 'False'
      Example: self.pool.get('model').write(cr, uid, ids, {'field_m2o' : False})
Note: Using a webservice works without problem
possible line with error
file: orm.py
line 4152 upd1.append(self._columns[field]._symbol_set[1](vals[field]))

2) The result you observed
set 0 in field m2o
3) The result you expected
completely empty the m2o field
4) The platform your are using
Ubuntu 12.04
 5) The OpenERP version
OpenERP 7.0
Server revno: 5179
addons revno: 9703
web addons revno: 4027