Wrong result message when creating new user

[Jaewoook]

Describe the bug A clear and concise description of what the bug is. 문제가 발생하는 상황에 대한 요약 설명을 적어주세요.

When using domain-admin account, The webui displays wrong result message when creating new user. (The domain-admin has no permission to create user)

To Reproduce Steps to reproduce the behavior: 문제를 재현하기 위한 순서를 자세히 적어주세요:

1. Log into domain-admin account
2. Go to Users menu
3. Click Create User button and fill the form
4. See error

Expected behavior A clear and concise description of what you expected to happen. 원래 기대했던 동작은 어떤 것인지 명확하게 적어주세요.

Webui should display the correct error reason, or disable the Create User button

Screenshots If applicable, add screenshots to help explain your problem. Just take a screenshot in your clipboard or copy a picture file and paste it here (Ctrl+V/Cmd+V) so that GitHub automatically attach and insert it. 가능하다면, 문제 상황을 보여주는 스크린샷을 첨부해주세요. 클립보드에 스크린샷을 찍거나 이미지 파일을 복사해서 여기에 붙여넣으면(Ctrl+V/Cmd+V) GitHub이 자동으로 이곳에 첨부 및 삽입해줍니다.

Client:

• OS: [e.g. macOS 10.14, Windows 10 (1903)]
• App version: [e.g. 19.08.3] (if you are using a GUI client app)
• Browser version: [e.g. Chrome 76, Safari, Edge] (if you are using a GUI web console)
• Python version: [e.g. 3.7.4] (if you are using the Python SDK)
• NodeJS version: [e.g. 12.0] (if you are using the Javascript SDK)

Server:

• OS: [e.g. Ubuntu 18.04, CentOS 7.6, macOS 10.14]
  • Output of uname -a: [e.g. Linux node01 4.15.0-54-generic #58-Ubuntu SMP Mon Jun 24 10:55:24 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux]
• Backend.AI version: [e.g. 19.09.0]
• Python version: [e.g. 3.6.8]
• Installation method: [e.g. on-premise, using cloud.backend.ai service, used scripts/install-dev.sh]

Additional context Add any other context about the problem here. 추가적으로 문제 상황을 설명할 수 있는 다른 맥락을 기술해주세요.

[dan-2ee]

As a result of my test, a new user is created normally. (in main branch) Do you still get the wrong message without creating a new user? @Jaewoook

[Jaewoook]

As a result of my test, a new user is created normally. (in main branch) Do you still get the wrong message without creating a new user? @Jaewoook

Fundamentally, this issue is related to the Backend.AI permission system. However even if it is not this project's fault, I think the error message need to be displayed correct reason.

Additional information: the test account is domain-admin (which is not superadmin)