[FIX] mail_tracking: Show correctly blank image

Bad P2 > P3 conversion

mail_tracking/__manifest__.py

@@ -7,7 +7,7 @@
 {
     "name": "Email tracking",
     "summary": "Email tracking system for all mails sent",
-    "version": "12.0.1.1.2",
+    "version": "12.0.1.1.3",
     "category": "Social Network",
     "website": "http://github.com/OCA/social",
     "author": "Tecnativa, "

mail_tracking/controllers/main.py

@@ -5,9 +5,10 @@ import werkzeug
 from psycopg2 import OperationalError
 from odoo import api, http, registry, SUPERUSER_ID
 import logging
+import base64
 _logger = logging.getLogger(__name__)
 
-BLANK = b'R0lGODlhAQABAIAAANvf7wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw=='
+BLANK = 'R0lGODlhAQABAIAAANvf7wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw=='
 
 
 def _env_get(db, callback, tracking_id, event_type, **kw):
@@ -82,5 +83,5 @@ class MailTrackingController(http.Controller):
         # Always return GIF blank image
         response = werkzeug.wrappers.Response()
         response.mimetype = 'image/gif'
-        response.data = BLANK
+        response.data = base64.b64decode(BLANK)
         return response

mail_tracking/tests/test_mail_tracking.py

@@ -4,6 +4,7 @@
 import mock
 from odoo.tools import mute_logger
 import time
+import base64
 from odoo import http
 from odoo.tests.common import TransactionCase
 from ..controllers.main import MailTrackingController, BLANK
@@ -175,7 +176,7 @@ class TestMailTracking(TransactionCase):
     def test_mail_send(self):
         controller = MailTrackingController()
         db = self.env.cr.dbname
-        image = BLANK
+        image = base64.b64decode(BLANK)
         mail, tracking = self.mail_send(self.recipient.email)
         self.assertEqual(mail.email_to, tracking.recipient)
         self.assertEqual(mail.email_from, tracking.sender)