Metafields are exported as English, not the catalog default language

Description

Reproduced on Quicksilver

1. In Commerce manager, create a new catalog with Swedish as the default language. (Only Swedish is enabled.)
2. In the new catalog, create a product with the metaclass "fashion product".
3. Export the new catalog.
4. See that, in the exported file catalog.xml, the non metafield "AvailableSizes" (which does not support multiple languages) has data in the Swedish language.
5. Open the new catalog for editing.
6. Enable the English language on that catalog. Swedish remains the default language.
7. Export the new catalog again.

Expected:
All data for metafield in non-multiple languages remains in the catalog's default language, Swedish.

Actual:
In the exported file catalog.xml, the metafield "AvailableSizes" (which does not support multiple languages) has data in the English language.