Error editing profile when a profile field is locked

Note for the tester: Hi, please, don't hesitate to talk with John about this issue testing and ensure you can reproduce the problem without the patch, it is important that we don't cause a new regression. Setup 5 custom profile fields. One of each type, 2 locked, 3 not. Only use text input because other types are broken MDL-52175 Setup moodle to use authentication with external DB (or LDAP, maybe others). Setup auth module to take profile fields from external DB source. Create a user in that authentication method. Save values in each of the profile fields Create another user in that authentication method. Don't give it any values Setup auth module to block editing of two fields (one that was locked by custom profile fields, and one that was not) Fields locked by either external db auth or by the custom profile field setup should be read-only for a user who tries to edit their profile. But the other should be editible Lock some (not user profile) fields that same auth type Login as the first student Make sure you can still save and edit your profile Login as the second student Make sure you can still save and edit your profile Login as a manually created student. Set their country to "Select a country" Login as admin Lock country and description fields on manual auth (Site administration ► Plugins ► Authentication ► Manual accounts) Login as a manually created student. Make sure you can still save and edit your profile Login as admin and unlock the country box again Login as a manually created student. Set their country (e.g. Australia) Login as admin and lock the country box again Login as a manually created student. Make sure you can still save and edit your profile