Fixed the tests on PHP 5.3.3

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #7754
| License       | MIT
| Doc PR        | -

PHPUnit with PHP 5.3.3 couldn't handle garbage collecting properly.