Skip renaming column in EE when it was already created with the new name in CE

ee/db/migrate/20171129150921_rename_remote_mirror_available_to_mirror_available.rb

@@ -6,10 +6,15 @@ class RenameRemoteMirrorAvailableToMirrorAvailable < ActiveRecord::Migration
   disable_ddl_transaction!
 
   def up
+    # When moving from CE to EE, the column may already have been renamed.
+    return if column_exists?(:application_settings, :mirror_available)
+
     rename_column_concurrently :application_settings, :remote_mirror_available, :mirror_available
   end
 
   def down
+    return unless column_exists?(:application_settings, :mirror_available)
+
     cleanup_concurrent_column_rename :application_settings, :mirror_available, :remote_mirror_available
   end
 end

ee/db/post_migrate/20171201140229_cleanup_remote_mirror_available_rename.rb

@@ -6,10 +6,15 @@ class CleanupRemoteMirrorAvailableRename < ActiveRecord::Migration
   disable_ddl_transaction!
 
   def up
+    # When moving from CE to EE, the column may already have been renamed.
+    return unless column_exists?(:application_settings, :remote_mirror_available)
+
     cleanup_concurrent_column_rename :application_settings, :remote_mirror_available, :mirror_available
   end
 
   def down
+    return if column_exists?(:application_settings, :remote_mirror_available)
+
     rename_column_concurrently :application_settings, :mirror_available, :remote_mirror_available
   end
 end