UPD: first little 2to3 migration steps.

dav_base/console_scripts/admin.py

@@ -96,17 +96,17 @@ class AdminCommand(object):
 
         input_file = os.path.join('django_project_config', 'additional_settings.py')
         output_file = os.path.join(django_base_dir, django_main_module, 'settings.py')
-        with open(output_file, 'a') as f:
+        with open(output_file, 'ab') as f:
             f.write(pkg_resources.resource_string(__package__, input_file))
 
         input_file = os.path.join('django_project_config', 'urls.py')
         output_file = os.path.join(django_base_dir, django_main_module, 'urls.py')
-        with open(output_file, 'w') as f:
+        with open(output_file, 'wb') as f:
             f.write(pkg_resources.resource_string(__package__, input_file))
 
         input_file = os.path.join('django_project_config', 'settings-dav_base.py')
         output_file = os.path.join(django_base_dir, django_main_module, 'settings-dav_base.py')
-        with open(output_file, 'w') as f:
+        with open(output_file, 'wb') as f:
             f.write(pkg_resources.resource_string(__package__, input_file))
 
         return posix.EX_OK