[FIX] ir.model.data: update_dummy should mark `inherits` parents too

When a `noupdate` record is processed during an update,
the update_dummy method marks the record as "seen" so
it won't be deleted at the garbage collection step,
and seen as an obsolete external ID.

This needs to be done also for the parent records via
_inherits, because they have also received an implicit
external ID at creation, and must not be garbage
collected, even if their `noupdate` flag (db side)
is not set because the flag was added later.

This rare problem could be reproduced by creating a product
in a module, then referencing it in e.g. a sales order,
then updating the module after changing the product
record to be in a `noupdate` block.
At the end of the update the implicit product.template
record would be garbage collected, and trigger a cascade
deletion of its children - blocked by the SO reference
to the product.

openerp/addons/base/ir/ir_model.py

@@ -992,6 +992,10 @@ class ir_model_data(osv.osv):
             if record:
                 id = record.id
                 self.loads[(module,xml_id)] = (model,id)
+                for table, inherit_field in self.pool[model]._inherits.iteritems():
+                    parent_id = record[inherit_field].id
+                    parent_xid = '%s_%s' % (xml_id, table.replace('.', '_'))
+                    self.loads[(module, parent_xid)] = (table, parent_id)
         except Exception:
             pass
         return id