load_keystore: deepcopy object so that it differs from the one in db.data

db.data should not be modified directly

electrum/keystore.py

@@ -27,6 +27,7 @@
 from unicodedata import normalize
 import hashlib
 import re
+import copy
 from typing import Tuple, TYPE_CHECKING, Union, Sequence, Optional, Dict, List, NamedTuple
 from functools import lru_cache, wraps
 from abc import ABC, abstractmethod
@@ -1069,7 +1070,8 @@ def hardware_keystore(d) -> Hardware_KeyStore:
                               f'hw_keystores: {list(hw_keystores)}')
 
 def load_keystore(db: 'WalletDB', name: str) -> KeyStore:
-    d = db.get(name, {})
+    # deepcopy object to avoid keeping a pointer to db.data
+    d = copy.deepcopy(db.get(name, {}))
     t = d.get('type')
     if not t:
         raise WalletFileException(