Locally updated content_type select field options don't update in engine on subsequent wagon deploy

[greyskin]

Steps to reproduce:

1. Create a content_type with a select field with some options
2. Run wagon deploy [env] -r content_types
3. Create some content entries in the Back Office
4. Add another option to the select field locally
5. Run wagon deploy [env] -r content_types again
6. Inspect the model in the Back Office and observe that the new select option does not appear

Workaround:

1. Delete the select field locally
2. Run wagon deploy [env] -r content_types again
3. Re-add the select field locally and include the new option(s)
4. Run wagon deploy [env] -r content_types again
5. Inspect the model in the Back Office and observe that the new select option is now available

This workaround has the major drawback of wiping any select options that have been applied to content entries up until this point.