Adds an index on issue_id to changesets_issues (#24433).

git-svn-id: https://svn.redmine.org/redmine/trunk@16007 e93f8b46-1217-0410-a6f0-8f06a7374b81

db/migrate/20161126094932_add_index_on_changesets_issues_issue_id.rb

+class AddIndexOnChangesetsIssuesIssueId < ActiveRecord::Migration
+  def change
+    add_index :changesets_issues, :issue_id
+  end
+end