Do not strip forwarded message

When creating an issue from service desk email, we should keep
quoted/forwarded part of the message.

changelogs/unreleased/fix-service-desk-forward.yml

+---
+title: Do not strip forwarded message body when creating an issue from Service Desk
+  email.
+merge_request: 18196
+author:
+type: fixed

ee/lib/gitlab/email/handler/ee/service_desk_handler.rb

@@ -62,7 +62,7 @@ module Gitlab
               project,
               User.support_bot,
               title: issue_title,
-              description: message,
+              description: message_including_reply,
               confidential: true,
               service_desk_reply_to: from_address
             ).execute

ee/spec/fixtures/emails/service_desk_forwarded_new_issue.eml

+Delivered-To: incoming+email-test-project_id-issue-@appmail.adventuretime.ooo
+Return-Path: <jake@adventuretime.ooo>
+Received: from iceking.adventuretime.ooo ([unix socket]) by iceking (Cyrus v2.2.13-Debian-2.2.13-19+squeeze3) with LMTPA; Thu, 13 Jun 2013 17:03:50 -0400
+Received: from mail-ie0-x234.google.com (mail-ie0-x234.google.com [IPv6:2607:f8b0:4001:c03::234]) by iceking.adventuretime.ooo (8.14.3/8.14.3/Debian-9.4) with ESMTP id r5DL3nFJ016967 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for <incoming+gitlabhq/gitlabhq@appmail.adventuretime.ooo>; Thu, 13 Jun 2013 17:03:50 -0400
+Received: by mail-ie0-f180.google.com with SMTP id f4so21977375iea.25 for <incoming+email-test-project_id-issue-@appmail.adventuretime.ooo>; Thu, 13 Jun 2013 14:03:48 -0700
+Received: by 10.0.0.1 with HTTP; Thu, 13 Jun 2013 14:03:48 -0700
+Date: Thu, 13 Jun 2013 17:03:48 -0400
+From: Jake the Dog <jake@adventuretime.ooo>
+To: support@adventuretime.ooo
+Delivered-To: support@adventuretime.ooo
+Message-ID: <CADkmRc+rNGAGGbV2iE5p918UVy4UyJqVcXRO2=otppgzduJSg@mail.gmail.com>
+Subject: The message subject! @all
+Mime-Version: 1.0
+Content-Type: text/plain;
+ charset=ISO-8859-1
+Content-Transfer-Encoding: 7bit
+X-Sieve: CMU Sieve 2.2
+X-Received: by 10.0.0.1 with SMTP id n7mr11234144ipb.85.1371157428600; Thu,
+ 13 Jun 2013 14:03:48 -0700 (PDT)
+X-Scanned-By: MIMEDefang 2.69 on IPv6:2001:470:1d:165::1
+
+Service desk stuff!
+
+---------- Forwarded message ---------
+From: Jake the Dog <jake@adventuretime.ooo>
+To: <jake@adventuretime.ooo>
+
+
+forwarded content

ee/spec/lib/gitlab/email/handler/ee/service_desk_handler_spec.rb

@@ -12,6 +12,7 @@ describe Gitlab::Email::Handler::EE::ServiceDeskHandler do
 
   let(:email_raw) { email_fixture('emails/service_desk.eml', dir: 'ee') }
   let(:namespace) { create(:namespace, name: "email") }
+  let(:expected_description) { "Service desk stuff!\n\n```\na = b\n```\n\n![image](uploads/image.png)" }
 
   context 'service desk is enabled for the project' do
     let(:project) { create(:project, :public, namespace: namespace, path: 'test', service_desk_enabled: true) }
@@ -35,7 +36,7 @@ describe Gitlab::Email::Handler::EE::ServiceDeskHandler do
         expect(new_issue.confidential?).to be true
         expect(new_issue.all_references.all).to be_empty
         expect(new_issue.title).to eq("Service Desk (from jake@adventuretime.ooo): The message subject! @all")
-        expect(new_issue.description).to eq("Service desk stuff!\n\n```\na = b\n```\n\n![image](uploads/image.png)")
+        expect(new_issue.description).to eq(expected_description.strip)
       end
 
       it 'sends thank you email' do
@@ -125,6 +126,27 @@ describe Gitlab::Email::Handler::EE::ServiceDeskHandler do
 
       it_behaves_like 'a new issue request'
     end
+
+    context 'when the email is forwarded' do
+      let(:email_raw) { email_fixture('emails/service_desk_forwarded_new_issue.eml', dir: 'ee') }
+
+      it_behaves_like 'a new issue request' do
+        let(:expected_description) do
+          <<~EOF
+            Service desk stuff!
+
+            ---------- Forwarded message ---------
+            From: Jake the Dog <jake@adventuretime.ooo>
+            To: <jake@adventuretime.ooo>
+
+
+            forwarded content
+
+            ![image](uploads/image.png)
+          EOF
+        end
+      end
+    end
   end
 
   context 'service desk is disabled for the project' do