force verification after getting file from export remote

This way, if annex.verify is disabled, it's still checked, since this is
not a key/value store, it has to be checked.

Remote/Helper/ExportImport.hs

@@ -333,6 +333,6 @@ adjustExportImport rmt rs = do
 					)
 				(l:_) -> do
 					retrieveExport (exportActions r) k l dest p
-					return UnVerified
+					return MustVerify
 		, giveup $ "exported content cannot be verified due to using the " ++ decodeBS (formatKeyVariety (fromKey keyVariety k)) ++ " backend"
 		)