add_trusted_domain() for a new domain always needs to be followed by a setup_domain_child(). This was not always done, in particular not when walking to the forest root for additional trusts.
Created attachment 5652 [details] Patch for 3.5
Comment on attachment 5652 [details] Patch for 3.5 Looks good
Karolin, please pick for the release
Pushed to v3-5-test. Closing out bug report. Thanks!