This is one of the conflicts. The diff here doesn't actually show the difference between this pull request and what is in master.  In master this line is:
config.stretches = (Rails.env.development? || Rails.env.production? || Rails.env.staging?) ? 10 : 1
That is the approach we ended up @knowuh made the switch a little bit ago. The reason is because often we have existing development databases, so with only 1 stretch in development mode that invalids any existing passwords.