Preconditions:

1. User A has been created

2. User B has been created

3. Authorized User A is logged in with "Users: Can edit user profile" permission

Steps to reproduce:

1. User A goes to "Users" app and opens details pane of any active user

2. User A clicks "Actions" button on <Username> details pane and selects "Edit" option

3. User A enters User B username in "Username" field in "Extended information" accordion and adding whitespaces before and after username

4. User A clicks "Save & close" button on "Edit" page

Actual result:

Changes were successfully saved

Expected result:

Warning message "This username already exists" is displayed, changes were not saved