Add a test for bug 73529

ext/session/tests/bug73529.phpt

@@ -0,0 +1,36 @@
+--TEST--
+Bug #73529 session_decode() silently fails on wrong input
+--SKIPIF--
+<?php include('skipif.inc'); ?>
+--FILE--
+<?php
+
+ini_set("session.serialize_handler", "php_serialize");
+session_start();
+
+$result1 = session_decode(serialize(["foo" => "bar"]));
+$session1 = $_SESSION;
+session_destroy();
+
+ini_set("session.serialize_handler", "php");
+session_start();
+
+$result2 = session_decode(serialize(["foo" => "bar"]));
+$session2 = $_SESSION;
+session_destroy();
+
+var_dump($result1);
+var_dump($session1);
+var_dump($result2);
+var_dump($session2);
+
+?>
+--EXPECT--
+bool(true)
+array(1) {
+  ["foo"]=>
+  string(3) "bar"
+}
+bool(false)
+array(0) {
+}