If it is possible to cancel the effect of the O_TEMPORARY flag, we can use it to implement this feature on all platforms. But if it is not possible, we have several options:

1. Just close this issue and do nothing more. This was undocumented and non-portable feature.

2. Implement delete as readonly property. This is similar to 1 but makes the failure loud.

3. Implement this feature on non-Windows, document that it is non-Windows only feature, and raise an exception in delete setter on Windows.

4. Same as 3, but emit deprecation warning in delete setter on non-Windows. In future this should be replaced with solution 2.