Created users cannot be modified

When using the MySQL authentication, if a non-admin user (with user creation rights) creates a new user, they will be unable to edit that user. Attempting to do so results in a page with an infinitely-spinning cog.

To reproduce:

1. As the system administrator, create a new user "X".
2. Grant user creation permission to "X". Grant no other permissions.
3. Log out
4. Log in as "X"
5. Create a new user
6. Click on the newly-created user

Expected results:

The edit screen for the newly-created user is displayed.

Actual results:

A screen with an infinitely-spinning cog is displayed. The user cannot be edited.