Sample code:

```
import os
from tempfile import TemporaryDirectory

name = TemporaryDirectory().name
print(os.path.exists(name))  # prints False

td = TemporaryDirectory()
name_2 = td.name
print(os.path.exists(name_2))  # prints True
```

Expected behavior: `True` is printed for both print statements.

I have run this example on:

* CPython 3.6.3
* CPython 3.5.3
* pypy 3.5.3

The unexpected behavior occurs on CPython 3.5.3 and CPython 3.6.X but not on pypy.

(bug found with Tim Weidner https://github.com/timaa2k).