patch mailer to fix mail threading (#6582)

init.rb

@@ -2,9 +2,10 @@ require 'redmine'
 
 require_dependency 'welcome_controller_patch'
 require_dependency 'project_model_patch'
+require_dependency 'mailer_patch'
 
 Redmine::Plugin.register :redmine_entrouvert do
   name 'Redmine Entr\'ouvert plugin'
   author 'Entr\'ouvert'
-  version '0.1.0'
+  version '0.2.0'
 end

lib/mailer_patch.rb

@@ -0,0 +1,23 @@
+module MailerPatch
+  def self.included(base)
+    base.class_eval do
+      def self.token_for(object, rand=true)
+        timestamp = object.send(object.respond_to?(:created_on) ? :created_on : :updated_on)
+        hash = [
+          "redmine",
+          "#{object.class.name.demodulize.underscore}-#{object.id}",
+          timestamp.strftime("%Y%m%d%H%M%S")
+        ]
+        # disabled, see https://dev.entrouvert.org/issues/6582
+        #if rand
+        #  hash << Redmine::Utils.random_hex(8)
+        #end
+        host = Setting.mail_from.to_s.gsub(%r{^.*@}, '')
+        host = "#{::Socket.gethostname}.redmine" if host.empty?
+        "#{hash.join('.')}@#{host}"
+      end
+    end
+  end
+end
+
+Mailer.send(:include, MailerPatch)