[FIX] auditlog: log computed fields stored in db as expected

Fixing #1134.
Odoo stores values of computed fields at the end of the transaction
only, as such performing a 'read()' to make a data snapshot on the record
created in the current transaction doesn't return the expected result
regarding these fields.
Also as a side-effect 'read()' alters the environment cache and break the
values on the record inducing issues in the whole user
transaction/workflow.

This fix replaces the use of 'read()' to do the data snapshot directly
from the cache of the record (computed values are already there).

auditlog/models/rule.py

@@ -214,9 +214,14 @@ class AuditlogRule(models.Model):
             self = self.with_context(auditlog_disabled=True)
             rule_model = self.env['auditlog.rule']
             new_record = create_full.origin(self, vals, **kwargs)
-            new_values = dict(
-                (d['id'], d) for d in new_record.sudo()
-                .with_context(prefetch_fields=False).read(list(self._fields)))
+            # Take a snapshot of record values from the cache instead of using
+            # 'read()'. It avoids issues with related/computed fields which
+            # stored in the database only at the end of the transaction, but
+            # their values exist in cache.
+            new_values = {new_record.id: {}}
+            for fname, field in new_record._fields.items():
+                new_values[new_record.id][fname] = field.convert_to_read(
+                    new_record[fname], new_record)
             rule_model.sudo().create_logs(
                 self.env.uid, self._name, new_record.ids,
                 'create', None, new_values, {'log_type': log_type})