Creating a pattern.config and defining a M2M export field in one go doesn't give expected result

[kevinkhao]

1. Click "Create" when in new pattern.config view
2. Choose all required options, take for example Contact as model
3. Don't click "Save" yet
4. Create a new export line "Tags/Name"
5. Click "Save"
6. Generate template file
7. Observe you get only one "tag_ids" column instead of the correct tag_ids|1|name

Issue does not occur if you click "Save" on step 3

[sebastienbeau]

Fixed here : https://github.com/shopinvader/pattern-import-export/commit/4bb18928e4d2da32cb74c1a3a24ac512230da5cd