Searching for issue/mr by iid in markdown

app/models/project.rb

@@ -201,7 +201,7 @@ class Project < ActiveRecord::Base
 
   def issue_exists?(issue_id)
     if used_default_issues_tracker?
-      self.issues.where(id: issue_id).first.present?
+      self.issues.where(iid: issue_id).first.present?
     else
       true
     end

lib/gitlab/markdown.rb

@@ -181,7 +181,7 @@ module Gitlab
     end
 
     def reference_merge_request(identifier)
-      if merge_request = @project.merge_requests.where(id: identifier).first
+      if merge_request = @project.merge_requests.where(iid: identifier).first
         link_to("!#{identifier}", project_merge_request_url(@project, merge_request), html_options.merge(title: "Merge Request: #{merge_request.title}", class: "gfm gfm-merge_request #{html_options[:class]}"))
       end
     end