If when we request a LocalStatus folder, the folder has to be created,
we look whether the other backend has data, and if it does we migrate
it to the new backend.
The old backend data is left untouched, so that if you change back say
from sqlite to plaintext, the older data is still there. That should
not lead to data loss, only a slower sync while the status folder gets
updated.
Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
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