we only want to sign the inputs that we've reserved via utxopsbt or fundpsbt. we mark them with a flag (reusing the now defunct max-len flag is fine), then look for inputs with that flag to pass to signonly
we only want to sign the inputs that we've reserved via utxopsbt or fundpsbt. we mark them with a flag (reusing the now defunct max-len flag is fine), then look for inputs with that flag to pass to signonly