Document H5Punregister modifying default properties

[mattjala]

H5Punregister() says that existing property lists are unaffected. However, property lists get default property values from their parent class(es). If list has a property with a default value, then calling H5Punregister() to remove that property from the class will also remove it from the list.

This is probably something we'll want to change eventually, but for now we can at least document the actual behavior.

[qkoziol]

H5Punregister() says that existing property lists are unaffected. However, property lists get default property values from their parent class(es). If list has a property with a default value, then calling H5Punregister() to remove that property from the class will also remove it from the list.

This is probably something we'll want to change eventually, but for now we can at least document the actual behavior.

Yes, this looks like a bug. Existing property lists with the property should retain the value.