Add test guaranteeing that loop vars are only freed after potential return type exceptions

Zend/tests/return_types/029.phpt

@@ -0,0 +1,19 @@
+--TEST--
+Return types must not double free loop variables
+--FILE--
+<?php
+
+function foo(): string {
+	foreach ([new stdClass] as $class) {
+		try {
+			return $class; // invalid return type
+		} catch (TypeError $e) {
+			return "no leak or segfault";
+		}
+	}
+}
+print foo();
+
+?>
+--EXPECT--
+no leak or segfault