1. Add a Documents and Media portlet to the page
2. Create a new document type with two 'Text' fields.
3. Add a new document with the document type you created.
4. Export this portlet to a lar file.
5. Go to another site (default public/private is fine).
6. Add a Documents and Media portlet
7. Set Configuration -> Scope | "Scope: Select Page" and "Scope Page: Current Page (Home)".
8. Import the lar file we exported earlier. Constraint Violation Exception is thrown.
This should be reproducible without step 7.