a7199696d3
The keystore logic would need to be significantly changed to nicely
interoperate with StoredDict/json_db logic.
(just see KeyStore.__init__() and KeyStore.dump())
For now we exempt the keystore from the recursive StoredDict conversion, as
it is a smaller change that is also easier to review for correctness.
fixes #6066
fixes #6401
also reverts 2d3c2eeea9 (which was an even hackier workaround for #6066)