MWS: Manage ACL screen returning HTTP 403 error

[Jermolene]

Steps to reproduce:

1. Start with a fresh install of MWS
2. Run npm install and npm start
3. Visit http://127.0.0.1:8080/ in a browser
4. Click the button "Add Admin Account"
5. Enter suitable details for an admin account and click "Add User"
6. Click the link to "recipe-tau" which opens http://127.0.0.1:8080/wiki/recipe-tau
7. Click the globe icon in the sidebar to bring up the "Manage ACL" screen
8. In the box "Recipe ACL", enter the role USER and the permission READ, and click the button "Add ACL Record"
9. In the box "Recipe ACL", enter the role USER and the permission WRITE, and click the button "Add ACL Record"
10. Observe the HTTP Error 403
11. Close the tab and return to http://127.0.0.1:8080/
12. Refresh the page
13. Observe that "recipe-tau" is no longer listed

cc @webplusai