Links Added inside RichText field pointing to Content in different tree root will be displayed wrong and clicking on them will result in 404 page.

Steps to reproduce
1. Clean installation of eZ Platform 2.5.6
2. Log in to the Backoffice as admin. In Content tree root (Home) create and publish Folder Folder A.
3. In Content tree root (Home) create and publish Folder Folder B.
4. Set up your project as follows (ezplatform.yml):

siteaccess:
        list: [site_a, site_b, admin]
        groups:
            site_group: [site_a, site_b]
            admin_group: [admin]
        default_siteaccess: site_a
        match:
            URIElement: 1

    system:
        site_a:
            languages: [eng-GB]
            content:
                tree_root:
                    location_id: 56
                    excluded_uri_prefixes: [ /media, /images ]
        site_b:
            languages: [eng-GB]
            content:
                tree_root:
                    location_id: 57
                    excluded_uri_prefixes: [ /media, /images ]

5. In Backoffice create and publish a new Article Article 2 in Folder A.
6. Create and publish a new Article Article 1 in Folder A. In Body RichText field create a link pointing to Article 2.
7. Create a new location in Folder B for Article 1.
8. Open Article 1 in Siteaccess site_b. Click on the link to Article 2.

Expected Result
Article 2 will be shown in site_a.

Result
The wrong URL for the link will be used http://<domain>/site_b/folder-a/article-2, which will result in NotFoundHttpException.