bip39_recovery: also scan change addresses

fixes #7804

electrum/bip39_recovery.py

@@ -3,6 +3,7 @@
 # file LICENCE or http://www.opensource.org/licenses/mit-license.php
 
 from typing import TYPE_CHECKING
+import itertools
 
 from . import bitcoin
 from .constants import BIP39_WALLET_FORMATS
@@ -44,11 +45,15 @@ async def scan_for_active_accounts(network: 'Network', get_account_xpub, wallet_
 
 
 async def account_has_history(network: 'Network', account_node: BIP32Node, script_type: str) -> bool:
-    gap_limit = 20
+    # note: scan both receiving and change addresses. some wallets send change across accounts.
+    path_suffixes = itertools.chain(
+        itertools.product((0,), range(20)),  # ad-hoc gap limits
+        itertools.product((1,), range(10)),
+    )
     async with OldTaskGroup() as group:
         get_history_tasks = []
-        for address_index in range(gap_limit):
-            address_node = account_node.subkey_at_public_derivation("0/" + str(address_index))
+        for path_suffix in path_suffixes:
+            address_node = account_node.subkey_at_public_derivation(path_suffix)
             pubkey = address_node.eckey.get_public_key_hex()
             address = bitcoin.pubkey_to_address(script_type, pubkey)
             script = bitcoin.address_to_script(address)