Merge branch 'backup-database-timeout-fix' into 'master'

Fix timeout issue for rake task gitlab:backup:create

This is a fix for a database timeout which can occur when the backup
create task is taking very long (1-2 hours).
It seems that ActiveRecord is loosing the connection after a hour
idleness and need to be reconnected before use.

See merge request !2757

CHANGELOG

@@ -2,6 +2,7 @@ Please view this file on the master branch, on stable branches it's out of date.
 
 v 8.4.4
   - Update omniauth-saml gem to 1.4.2
+  - Prevent long-running backup tasks from timing out the database connection
 
 v 8.4.3
   - Increase lfs_objects size column to 8-byte integer to allow files larger

lib/backup/manager.rb

 module Backup
   class Manager
     def pack
+      # Make sure there is a connection
+      ActiveRecord::Base.connection.reconnect!
+
       # saving additional informations
       s = {}
       s[:db_version]         = "#{ActiveRecord::Migrator.current_version}"