Fix np restricted migration

Hello,

this fixes https://lab.nexedi.com/nexedi/erp5/commit/79fa584e70ec7d09c48d41dbd6abe2ea7c098a61 and it also adds a test to ensure this works now.

• Here is a test run where only the test has been added, but not the fixup commit and we can see the test is failing.
• Here is a test run where both the fixup and the new test were added, we can see the test passes now.

Is it ok to add the test like this?

Best, Levin

/cc @klaus