Product module migration script is missing an import statement for logging

[Don Kirkby]

When I try to upgrade from 5.0.16 to 6.0, I get the following error:

  File "product/migrations/6.0.1.1/pre-migration.py", line 24, in <module>
NameError: name 'logging' is not defined

Steps to reproduce:
1. Create a new database in 5.0 with no sample data and the manufacturing industry profile.
2. Leave the default values for all the setup steps, and set the chart of accounts to "None".
3. Create a new product category called "All Products".
4. Create a new product called "paperclip", and use the category you just created.
5. Run the migration using the options, "--update all --stop-after-init". The error occurs as listed above.

The full command line I use for the migration is as follows:
python openerp-server.py --database migrationtest --update all --stop-after-init --addons ~/upgrade-addons-6.0 --config ~/openerp-server.config

Analysis:
I think this can be fixed by just adding an import statement to the pre-migration.py file.