Matthias Clasen authored Jul 12, 2019 and Philip Withnall committed Jul 15, 2019

We want to use the keyfile backend in sandboxes,
but we want to avoid people losing their existing
settings that are stored in dconf. Flatpak does
a migration from dconf to keyfile, but only if
the app explictly requests it.

From an app perspective, there are two steps to
the dconf->keyfile migration:
1. Request that flatpak do the migration, by adding
   the migrate-path key to the metadata
2. Stop adding the 'dconf hole' to the sandbox

To keep us from switching to the keyfile backend
prematurely, look at whether the app has stopped
requesting a 'dconf hole' in the sandbox.