CA-140596: Failed Lock cannot be garbage collected

Yes, it could be simplified. In that case, the client call would look like:
```
if self._try_to_open_lockfile()
```
and I thought that

```
if self._try_to_open_lockfile().succeeded
```
Speaks better for itself. On the other side, your version means less code, and the less code is the better. I'm fine either way.