[ORM] psycopg2.ProgrammingError: cannot change number of columns in view

When you try to modified a postgres view an error appear in the moment you update the module:

Traceback (most recent call last):
  File "./openerp-server.py", line 99, in <module>
    pooler.get_db_and_pool(db, update_module=tools.config['init'] or tools.config['update'])
  File "/home/nhomar/openerp/stable/5.0/instancias/desarrollo/server/bin/pooler.py", line 40, in get_db_and_pool
    addons.load_modules(db, force_demo, status, update_module)
  File "/home/nhomar/openerp/stable/5.0/instancias/desarrollo/server/bin/addons/__init__.py", line 740, in load_modules
    r = load_module_graph(cr, graph, status, report=report)
  File "/home/nhomar/openerp/stable/5.0/instancias/desarrollo/server/bin/addons/__init__.py", line 584, in load_module_graph
    init_module_objects(cr, package.name, modules)
  File "/home/nhomar/openerp/stable/5.0/instancias/desarrollo/server/bin/addons/__init__.py", line 373, in init_module_objects
    obj.init(cr)
  File "/home/nhomar/openerp/stable/5.0/instancias/desarrollo/server/bin/addons/l10n_ve_fiscal_reports/l10n_ve_fiscal_reports.py", line 96, in init
    """)
  File "/home/nhomar/openerp/stable/5.0/instancias/desarrollo/server/bin/sql_db.py", line 77, in wrapper
    return f(self, *args, **kwargs)
  File "/home/nhomar/openerp/stable/5.0/instancias/desarrollo/server/bin/sql_db.py", line 122, in execute
    res = self._obj.execute(query, params)
psycopg2.ProgrammingError: cannot change number of columns in view

For Exampl:

I defined a Class:

class some_sql_view(osv.osv):
    _name = "some.sql.view"
    _description = "View on SQL"
    _auto = False
    _rec_name = 'ai_nro_ctrl'
    _columns = {
        'field1':fields.char('Control No.', size=128, required=False, readonly=True),
        'field2':fields.char('Invoice Number', size=128, required=False, readonly=True),
    }
    def init(self, cr):
        '''
        Create or replace view some_sql_view
        '''
        cr.execute("""
            create or replace view fiscal_reports_purchase as (
                SELECT
                     ai."field1" AS field1,
                     rp."field2" AS field2,
               FORM
                     some_model;
                 )
        """)
some_sql_view()

It works fine i have a view with 2 Fields....
Then I try add an extra field called field3
I add 2 lines......

class some_sql_view(osv.osv):
    _name = "some.sql.view"
    _description = "View on SQL"
    _auto = False
    _rec_name = 'ai_nro_ctrl'
    _columns = {
        'field1':fields.char('Control No.', size=128, required=False, readonly=True),
        'field2':fields.char('Invoice Number', size=128, required=False, readonly=True),
        'field3':fields.char('Invoice Number', size=128, required=False, readonly=True), ################NEW LINE
    }
    def init(self, cr):
        '''
        Create or replace view some_sql_view
        '''
        cr.execute("""
            create or replace view fiscal_reports_purchase as (
                SELECT
                     "field1" AS field1,
                     "field2" AS field2,
                     "field3" AS field3 ################NEW LINE
               FORM
                     some_model;
                 )
        """)
some_sql_view()

In this moment when i apply:

./openerp-server.py -u module -d dbname

This error appear...

I need in tis case conect to postgres and delete mannually the view some_sql_view and try again and it works......

Thanks...