Source

File: wp-includes/Requests/Transport/fsockopen.php

public function connect_error_handler($errno, $errstr) {
		// Double-check we can handle it
		if (($errno & E_WARNING) === 0 && ($errno & E_NOTICE) === 0) {
			// Return false to indicate the default error handler should engage
			return false;
		}

		$this->connect_error .= $errstr . "\n";
		return true;
	}