Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1492848

Description of problem: When filling out the user creation dialog, if the user forgets to enter a required filed (such as the "Authorized by" or Username, an error is printed (which is correct). However, this seems to clear whatever roles the have been selected.

Version-Release number of selected component (if applicable): Foreman nightly

How reproducible: Always

Steps to Reproduce:
1. Open Users dialog
2. Fill out the form and select some roles, but leave a required fieid blank (like username)
3. Press submit

Actual results: The selected roles get cleared

Expected results: The selected roles persist.