Issue description:

1) Navigate to Project Admin page of any project.
2) Click on Roles tab and click on Add Users in any roles.
3) Enter the full username in the field box.

Expected Result:
The username entered will be queried and the user full name will be displayed in the drop down list.

Actual result:
The error message "No Matches" is displayed in drop down list.

Please find the attached screenshots for further reference.

Note :
1. if we slowly enter the username then we are getting response and username is getting displayed in the dropdown, but if we type the username a bit fast then multiple ajax calls are going for each keyup and except the last call all the other calls are not getting aborted ( we can see the errors in console window);