Use _serve_file to serve custom 404 page

Author: humitos

readthedocs/core/views/__init__.py

@@ -12,7 +12,7 @@
 import logging
 
 from django.conf import settings
-from django.http import HttpResponseRedirect, Http404, JsonResponse, HttpResponse
+from django.http import HttpResponseRedirect, Http404, JsonResponse
 from django.shortcuts import render, get_object_or_404, redirect
 from django.views.generic import TemplateView
 
@@ -21,6 +21,7 @@
 from readthedocs.core.resolver import resolve_path
 from readthedocs.core.symlink import PrivateSymlink, PublicSymlink
 from readthedocs.core.utils import broadcast
+from readthedocs.core.views.serve import _serve_file
 from readthedocs.projects.constants import PRIVATE
 from readthedocs.projects.models import Project, ImportedFile
 from readthedocs.projects.tasks import remove_dirs
@@ -153,8 +154,8 @@ def server_error_404(request, exception=None, template_name='404.html'):  # pyli
     fullpath = os.path.join(basepath, filename)
 
     if os.path.exists(fullpath):
-        log.debug('Serving custom 404.html page for project: %', project.slug)
-        r = HttpResponse(open(fullpath).read(), content_type='text/html')
+        log.info('Serving custom 404.html page for project: %', project.slug)
+        r = _serve_file(request, filename, basepath)
     else:
         # Return the default 404 page generated by Read the Docs
         r = render(request, template_name)