Impersonating as nested external user fails (to view permissions)

Set up: a case where the LDAP addon is used, with a nested user structure, so hipposys:dirlevels > 0 in the user provider at /hippo:configuration/hippo:security/ldaps/hipposys:userprovider.

In Console, using Node --> View Permissions, when trying to impersonate as a nested user, the user cannot be found. See

Analysis
In the impersonation logic, the providerId for that user is unknown (or lost), then method org.hippoecm.repository.security.SecurityManager#assignPrincipals uses the internal security manager rather then the LDAP one.