(customized) User profile fields when set a new profile field to required, it does not work

As title, here are steps to reproduce:

1. Login as admin, then go to Site Administration => Users => User profile fields => Create a new profile field (select text input for example)
2. Fill in the short name, name, and so on, and in the pull-down menu, change the "Is this field required" from No to Yes.
3. Go into editing user profile page, and see if it is required (the answer is NO)...

Tested on latest 1.9.12, have not tried out 1.9.13+ yet...