Remove die_if_not_set check for var user_roles

Since the later logic will add role if the user role is not
found. "die_if_not_set" check will exit the main script.

Closes-Bug: #1389714

Change-Id: I995cf357d09267fee55e44575e3e301bcffebca3
Merge "Remove die_if_not_set check for var user_roles"