iOS unlock reverts earlier orientation instead of letting device do its job

Scenaio:

1. Rotate phone to landscape 
2. Force portrait by invoking `screen.orientation.lock('portrait')`
3. Turn phone into portrait mode
4. Release orientation lock using `screen.orientation.unlock()`

Result:

Plugin reverts last orientation and phone changes to landscape

Expected result:

Phone should decide by its own in which orientation it is after unlock so it should remain in portrait mode in the above example.