Import of content in specific language might fail

Description

Under some circumstances, an import of a specific content language might import nothing even though the exported content exists in selected language.

Steps to reproduce (in Alloy sample site):

1. Create a new instance of StartPage under the root.
2. Go to admin mode.
3. Create a new website.
4. Select a newly-created page as the startpage and select "use site specific assets".
5. Under the newly-created start page, create a new page called "ExportRoot" in language "en".
6. Under "ExportRoot", create a page "child" in language "en".
7. Upload an image to the "For this site" folder.
8. Drag & drop the image from step 5 to page "child" created in 4.
9. Publish the page.
10. Translate the page "ExportRoot" to sv. Name it "ExportRootSV".
11. Goto admin mode.
12. Delete the cms site created in step 2.
13. Export the page ExportRoot with "include sub items" and "Export files that the pages link to" selected.
14. Import the package somewhere in structure with "Update existing content items with matching ID" not selected and select language "sv".

Expected:
Page "ExportRoot" is imported with "ExportRootSv" as included language

Actual:
Nothing is imported