does not apply legacy_issue migration if plugin installed after legacy_issue incident

db/migrate/20130916094369_legacy_issues_costs_data_to_work_packages.rb

@@ -14,6 +14,8 @@ require Rails.root.join("db","migrate","migration_utils","utils").to_s
 class LegacyIssuesCostsDataToWorkPackages < ActiveRecord::Migration
 
   def up
+    return unless migration_applicable?
+
     execute <<-SQL
       UPDATE work_packages
       SET cost_object_id = (SELECT legacy_issues.cost_object_id
@@ -24,6 +26,8 @@ class LegacyIssuesCostsDataToWorkPackages < ActiveRecord::Migration
   end
 
   def down
+    return unless migration_applicable?
+
     execute <<-SQL
       UPDATE legacy_issues
       SET cost_object_id = (SELECT work_packages.cost_object_id
@@ -32,4 +36,11 @@ class LegacyIssuesCostsDataToWorkPackages < ActiveRecord::Migration
                             LIMIT 1)
     SQL
   end
+
+  private
+
+  def migration_applicable?
+    ActiveRecord::Base.connection.table_exists?('legacy_issues') &&
+    ActiveRecord::Base.connection.columns('legacy_issues').map(&:name).include?('cost_object_id')
+  end
 end