Commits backported:
* Add tests for LUKS binding and unbinding
- f5d42cb3ba
* Rework the logic for reading the existing key
- 834eda9db6
* fix for different output from 'luksAddKey' command w/cryptsetup v2.0.2 (
- 62bd6de0b8
* pins/tang: check that key derivation key is available
- c231352729
