Add support to change the status header for gatekeeper-ng.

mailer.py

 import hashlib
 import hmac
 import json
 import logging
 import time
 
 from google.appengine.api import app_identity
 from google.appengine.api import mail
 from google.appengine.ext import ndb
 import webapp2
@@ skipping 150 matching lines @@
       self.error(400)
       return
 
     # Emails can only come from the app ID, so we split on '@' here just in
     # case the user specified a full email address.
     from_addr_prefix = build_data.get('from_addr', 'buildbot').split('@')[0]
     from_addr = from_addr_prefix + '@%s.appspotmail.com' % (
         app_identity.get_application_id())
 
     subject_template = build_data.get('subject_template')
+    status_header = build_data.get('status_header')
 
     template = gatekeeper_mailer.MailTemplate(build_data['waterfall_url'],
                                               build_data['build_url'],
                                               build_data['project_name'],
                                               from_addr,
-                                              subject=subject_template)
+                                              subject=subject_template,
+                                              status_header=status_header)
 
 
     text_content, html_content, subject = template.genMessageContent(build_data)
 
     sentries = ['gatekeeper-ng@chromium-gatekeeper-sentry.appspotmail.com',
                 'stip@chromium.org']
 
     recipients = list(set(build_data['recipients'] + sentries))
 
     message = mail.EmailMessage(sender=from_addr,
                                 subject=subject,
                                 to=recipients,
                                 body=text_content,
                                 html=html_content)
     logging.info('sending email to %s', ', '.join(recipients))
     logging.info('sending from %s', from_addr)
     logging.info('subject is %s', subject)
     message.send()
     self.response.out.write('email sent')
 
 
 app = webapp2.WSGIApplication([('/mailer', MainPage),
                                ('/mailer/email', Email)],
                               debug=True)