Comment 4 for bug 511979

Similar error on a database with demo data:

Environment Information :
System : Windows-Vista-6.1.7600
OS Name : nt
Operating System Release : Vista
Operating System Version : 6.1.7600
Operating System Architecture : 32bit
Operating System Locale : en_US.cp1252
Python Version : 2.5.2
OpenERP-Client Version : 6.0.1
Last revision No. & ID :Bazaar Package not Found !Traceback (most recent call last):
  File "/opt/openerp/openobject-server/bin/netsvc.py", line 489, in dispatch
    result = ExportService.getService(service_name).dispatch(method, auth, params)
  File "/opt/openerp/openobject-server/bin/service/web_services.py", line 599, in dispatch
    res = fn(db, uid, *params)
  File "/opt/openerp/openobject-server/bin/osv/osv.py", line 122, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/opt/openerp/openobject-server/bin/osv/osv.py", line 176, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/opt/openerp/openobject-server/bin/osv/osv.py", line 167, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/opt/openerp/openobject-server/bin/addons/base/module/wizard/base_module_upgrade.py", line 98, in upgrade_module
    _db, pool = pooler.restart_pool(cr.dbname, update_module=True)
  File "/opt/openerp/openobject-server/bin/pooler.py", line 60, in restart_pool
    return get_db_and_pool(db_name, force_demo, status, update_module=update_module)
  File "/opt/openerp/openobject-server/bin/pooler.py", line 39, in get_db_and_pool
    addons.load_modules(db, force_demo, status, update_module)
  File "/opt/openerp/openobject-server/bin/addons/__init__.py", line 883, in load_modules
    processed_modules.extend(load_module_graph(cr, graph, status, report=report, skip_modules=processed_modules))
  File "/opt/openerp/openobject-server/bin/addons/__init__.py", line 719, in load_module_graph
    init_module_objects(cr, package.name, modules)
  File "/opt/openerp/openobject-server/bin/addons/__init__.py", line 414, in init_module_objects
    result = obj._auto_init(cr, {'module': module_name})
  File "/opt/openerp/trunk-addons-community/openerp6-module/sale.py", line 283, in _auto_init
    cr.execute("ALTER TABLE account_invoice_line ALTER COLUMN discount TYPE numeric(16,6);")
  File "/opt/openerp/openobject-server/bin/sql_db.py", line 76, in wrapper
    if self.__closed:
  File "/opt/openerp/openobject-server/bin/sql_db.py", line 129, in execute
    try:
NotSupportedError: cannot alter type of a column used by a view or rule
DETAIL: rule _RETURN on view report_account_invoice_product depends on column "discount"