Before it is not apparant that the migration introduced for v64 is
associated with that particular version. This is because the guard
condition used to bail out from the upgrade is more closely related
to a previous migration.
This is due to a flaw with the desigh of `resetTransient()`, whereby
it always resets the database to the schema _of the current F-Droid
version being run_, not of the tables as they stood at the time of
the particular migration being introduced.
This clarifies the guard condition for v64 by instead explicitly asking
if the columns of interest exist yet in this particular invocation of
`onUpgrade()`.
a317877120