Selected site should not be available to be selected again

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 6.2.X EE, 7.0.0 M3
• Fix Version/s: 6.2.4 CE GA5, 6.2.X EE, 7.0.0 M1
• Component/s: Frontend Infrastructure
• Labels:
  • liferay-fixpack-portal-46-6210
• Environment: Tomcat 7.0.42 + MySQL 5.5.34. Portal master GIT ID: 02aaeba7d6adc90e223547a6d987567bd8b85c43.
• Branch Version/s:
  6.2.x
• Backported to Branch:
  Committed
• Story Points: 7
• Fix Priority: 3
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/16731

Steps to reproduce:

1. Create a user and then edit.
2. Click Sites under User Information.
3. Click Select and choose Liferay.
4. Click Select again.

Expected result:
Liferay should not be available to be selected.

Actual result:
Liferay is available to be selected. And we can select it again. User may be confused and think that it wasn't selected the first time. Though when the settings are saved, the site will only appear once in the list. This problem can be also reproduced when we select roles.