add migration before 20171207150343

db/post_migrate/20171207150300_remove_project_labels_group_id_copy.rb

+# Copy of 20180202111106 - this one should run before 20171207150343 to fix issues related to
+# the removal of groups with labels.
+
+class RemoveProjectLabelsGroupIdCopy < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    update_column_in_batches(:labels, :group_id, nil) do |table, query|
+      query.where(table[:type].eq('ProjectLabel').and(table[:group_id].not_eq(nil)))
+    end
+  end
+
+  def down
+  end
+end