[IMP] runbot_merge: log ACL error in PR controller

Currently this just silently returns a 404. Since repos are gated by
default (only accessible to internal users) this can get very
confusing when trying to setup a new repo or when forgetting this
information when writing tests.

runbot_merge/controllers/dashboard.py

@@ -7,6 +7,7 @@ import colorsys
 import hashlib
 import io
 import json
+import logging
 import math
 import pathlib
 from email.utils import formatdate
@@ -22,6 +23,9 @@ from PIL import Image, ImageDraw, ImageFont
 from odoo.http import Controller, route, request
 from odoo.tools import file_open
 
+
+_logger = logging.getLogger(__name__)
+
 LIMIT = 20
 class MergebotDashboard(Controller):
     @route('/runbot_merge', auth="public", type="http", website=True, sitemap=True)
@@ -101,6 +105,12 @@ class MergebotDashboard(Controller):
         if not pr_id:
             raise werkzeug.exceptions.NotFound()
         if not pr_id.repository.group_id <= request.env.user.groups_id:
+            _logger.warning(
+                "Access error: %s (%s) tried to access %s but lacks access",
+                request.env.user.login,
+                request.env.user.name,
+                pr_id.display_name,
+            )
             raise werkzeug.exceptions.NotFound()
 
         if png: