replace deprectated user=

app/models/member_role.rb

@@ -98,7 +98,7 @@ class MemberRole < ActiveRecord::Base
       end
     end
 
-    users = inherited_roles_by_member.keys.map(&:user)
+    users = inherited_roles_by_member.keys.map(&:principal)
 
     Watcher.prune(user: users, project_id: member.project_id) unless users.empty?
   end

features/step_definitions/role_steps.rb

@@ -33,7 +33,7 @@ Given /^the [Uu]ser "([^\"]*)" is a "([^\"]*)" (?:in|of) the [Pp]roject "([^\"]*
   p = Project.find_by(name: project) || Project.find_by(identifier: project)
   as_admin do
     Member.new.tap do |m|
-      m.user = u
+      m.principal = u
       m.roles << r
       m.project = p
     end.save!