Add rbf_merge_txid to PartialTransaction, instead of calling

get_unconfirmed_base_tx_for_batching a second time from GUI.

electrum/gui/qt/confirm_tx_dialog.py

@@ -567,8 +567,7 @@ class TxEditor(WindowModalDialog):
         if any(txin.block_height<=0 for txin in self.tx.inputs()):
             warnings.append(_('This transaction spends unconfirmed coins.'))
         # warn if we merge from mempool
-        base_tx = self.wallet.get_unconfirmed_base_tx_for_batching()
-        if self.config.get('batch_rbf', False) and base_tx:
+        if self.tx.rbf_merge_txid:
             warnings.append(_('This payment was merged with another existing transaction.'))
         # TODO: warn if we send change back to input address
         self.warning = _('Warning') + ': ' + '\n'.join(warnings) if warnings else ''

electrum/transaction.py

@@ -1651,6 +1651,7 @@ class PartialTransaction(Transaction):
         self._inputs = []  # type: List[PartialTxInput]
         self._outputs = []  # type: List[PartialTxOutput]
         self._unknown = {}  # type: Dict[bytes, bytes]
+        self.rbf_merge_txid = None
 
     def to_json(self) -> dict:
         d = super().to_json()

electrum/wallet.py

@@ -1664,6 +1664,9 @@ class Abstract_Wallet(ABC, Logger, EventListener):
         else:
             raise Exception(f'Invalid argument fee: {fee}')
 
+        # set if we merge with another transaction
+        rbf_merge_txid = None
+
         if len(i_max) == 0:
             # Let the coin chooser select the coins to spend
             coin_chooser = coinchooser.get_coin_chooser(self.config)
@@ -1686,6 +1689,7 @@ class Abstract_Wallet(ABC, Logger, EventListener):
                 txi = base_tx.inputs()
                 txo = list(filter(lambda o: not self.is_change(o.address), base_tx.outputs()))
                 old_change_addrs = [o.address for o in base_tx.outputs() if self.is_change(o.address)]
+                rbf_merge_txid = base_tx.txid()
             else:
                 txi = []
                 txo = []
@@ -1727,6 +1731,7 @@ class Abstract_Wallet(ABC, Logger, EventListener):
 
         # Timelock tx to current height.
         tx.locktime = get_locktime_for_new_transaction(self.network)
+        tx.rbf_merge_txid = rbf_merge_txid
         tx.set_rbf(rbf)
         tx.add_info_from_wallet(self)
         run_hook('make_unsigned_transaction', self, tx)