Federation - Error when adding a distant user to a circle

How is it now?

When adding a distant user to a circle, the base url of its @id is changed. For example, if I add:
https://api.test-nantes.happy-dev.fr/users/alex/, after saving, in the members of a circle, I can see:
https://api.test-paris.happy-dev.fr/users/alex/

How should it be?

It shouldn't do anything but save with the @id given in the request

Steps to reproduce

1. In config.json, change circles and users endpoints:

"circles": "https://api.test-paris.happy-dev.fr/sources/circles/",
"users": "https://api.test-paris.happy-dev.fr/sources/users/"

2. Go in a circle where you have the right to add a member, and add one from test-nantes
3. Check the new data saved at https://api.test-paris.happy-dev.fr/circles/X/
   The new member should have a wrong @id