Some courses have multiple orgs and it's not clear what we do / should do regarding course editors in the sidebar. In at least one case, the second org has no course editors which leads to a 404 for the second call to the organizations/.../users/ endpoint, and the result in the UI is that the course editors section does not render at all.
I think we should either load all course editors from all orgs into the select box, or if that is problematic, only load those from the first org for which we fetch at least one defined course editor.
Example where the 404 breaks the UI: https://publisher.edx.org/courses/e347cc55-d50e-45f2-b451-28f1df6e168f
confirm that in the case of multiple orgs, the 2 sets of course editors are combined
confirm that when a course has no ediitors, any user from either org can edit
change the behavior of the 404 - org exists, but course editors is empty
return an empty list instead of 404'ing
ensure that a 404 from one of the course editor GET calls does not break the UI
show the editors that were fetched successfully