QML: Check passwords with WalletDB instances that have no storage,

to avoid unwanted side effects.

In qedaemon, call load_wallet with upgrade=True when loading a
wallet. Apparently, this was not done before; db upgrades were
performed as a side-effect of password verification...

electrum/gui/qml/qedaemon.py

@@ -203,7 +203,7 @@ class QEDaemon(AuthMixin, QObject):
 
             try:
                 local_password = password  # need this in local scope
-                wallet = self.daemon.load_wallet(self._path, local_password)
+                wallet = self.daemon.load_wallet(self._path, local_password, upgrade=True)
 
                 if wallet is None:
                     self._logger.info('could not open wallet')

electrum/gui/qml/qewalletdb.py

@@ -43,7 +43,6 @@ class QEWalletDB(QObject):
         self._validPassword = True
 
         self._storage = None
-        self._db = None
 
         self._ready = False
 
@@ -143,7 +142,7 @@ class QEWalletDB(QObject):
         else:  # storage not encrypted; but it might still have a keystore pw
             # FIXME hack... load both db and full wallet, just to tell if it has keystore pw.
             try:
-                db = WalletDB(self._storage.read(), storage=self._storage, upgrade=True)
+                db = WalletDB(self._storage.read(), storage=None, upgrade=True)
             except WalletRequiresSplit as e:
                 raise WalletFileException(_('This wallet requires to be split. This is currently not supported on mobile'))
             wallet = Wallet(db, config=self._config)
@@ -165,11 +164,11 @@ class QEWalletDB(QObject):
         """can raise WalletFileException"""
         # needs storage accessible
         try:
-            self._db = WalletDB(self._storage.read(), storage=self._storage, upgrade=True)
+            db = WalletDB(self._storage.read(), storage=None, upgrade=True)
         except WalletRequiresSplit as e:
             self._logger.warning('wallet requires split')
             raise WalletFileException(_('This wallet needs splitting. This is not supported on mobile'))
-        if self._db.get_action():
+        if db.get_action():
             self._logger.warning('action pending. QML version doesn\'t support continuation of wizard')
             raise WalletFileException(_('This wallet has an action pending. This is currently not supported on mobile'))