admin fixture fails to create root user in master

Currently in master you cannot seed a production DB, as you get the following error:

== Seed from /opt/gitlab/embedded/service/gitlab-rails/db/fixtures/production/001_admin.rb
    Could not create the default administrator account:
    
    --> Password can't be blank

This might be related to changes introduced in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9598

cc\ @jneen @smcgivern