signpsbt do not allow to sign an utxo already spent in an unconfirmed transaction

[divoc91ab]

wallet-tool.py signpsbt do not allow the signing of a transaction spending an utxo spent in another unconfirmed transaction.

The psbt is correctly parsed but The PSBT is not yet fully signed, we signed: 0 inputs. is the result of the script.

Version 0.9.11
(It is the first issue that I open, so if it is missing any detail let me know)

[kristapsk]

According to code, signing PSBT that double spends wallet input in a new transaction that conflicts with another unconfirmed transaction from mempool should work ("utxos that we've stopped tracking"). Probably there is some bug or edge case.

joinmarket-clientserver/src/jmclient/wallet.py

Lines 1559 to 1577 in 5bfa08c

	# in the rare situation that we want to sign a psbt using private keys
	# to utxos that we've stopped tracking, let's also find inputs that
	# belong to us and add those private keys as well
	for vin in new_psbt.inputs:
	try:
	path = self.script_to_path(vin.utxo.scriptPubKey)
	key = self._get_key_from_path(path)
	if key not in privkeys:
	privkeys.append(key)
	except AssertionError:
	# we can safely assume that an exception means we do not
	# have the ability to sign for this input
	continue
	except AttributeError:
	# shouldn't happen for properly constructed psbts
	# however, psbts with no utxo information will raise
	# an AttributeError exception. we simply ignore it.
	continue