Fix rubocop offenses

app/models/ci/pipeline.rb

@@ -70,7 +70,7 @@ module Ci
         pipeline.update_duration
       end
 
-      before_transition :canceled => any - [:canceled] do |pipeline|
+      before_transition canceled: any - [:canceled] do |pipeline|
         pipeline.auto_canceled_by = nil
       end
 

db/migrate/20170402231018_remove_index_for_users_current_sign_in_at.rb

@@ -14,7 +14,7 @@ class RemoveIndexForUsersCurrentSignInAt < ActiveRecord::Migration
       if Gitlab::Database.postgresql?
         execute 'DROP INDEX CONCURRENTLY index_users_on_current_sign_in_at;'
       else
-        remove_index :users, :current_sign_in_at
+        remove_concurrent_index :users, :current_sign_in_at
       end
     end
   end