I am including a PHP file that in stored in the public:// directory.
(Yes, I know that's generally a bad thing, but there are reasons, and this is done on a local development server.)
I get this warning.
User warning: stream_set_option() not supported for local file based stream wrappers in Drupal\Core\StreamWrapper\LocalStream->stream_set_option() (line 356 of core/lib/Drupal/Core/StreamWrapper/LocalStream.php).
I don't understand what's going on.