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<!-- Describe the issue -->

Starting with the following unsigned transaction:

```
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
```

I first call:

```
walletprocesspsbt "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" true ALL true
```

Which generates:

```
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
```

Which is "complete: true" and parses fine. But then if I run `walletprocesspsbt` on the result AGAIN (don't ask why ... or do, but this should be idempotent):

```
walletprocesspsbt "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" true ALL true
```

I get the following:

```
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
```

Which is still reported as "complete: true", but when I try to decode or finalize it:

```TX decode failed PSBT is not sane.: unspecified iostream_category error (code -22)```

I would expect `walletprocesspsbt [foo] true ALL true` to be idempotent, or at least produce output that's parseable.

This is all testnet and I have attached the wallet.dat in case it's useful (it only has two UTXOs and very few keys.).

I am going to continue trying to debug this, but I figured since I haven't gotten it yet I should document it. Please let me know if someone else starts looking into it.

{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp))
        return NullUniValue;
    if (request.fHelp || request.params.size() < 1 || request.params.size() > 2) {
        throw std::runtime_error(
            "bumpfee \"txid\" ( options ) \n"
            "\nBumps the fee of an opt-in-RBF transaction T, replacing it with a new transaction B.\n"
            "An opt-in RBF transaction with the given txid must be in the wallet.\n"
            "The command will pay the additional fee by decreasing (or perhaps removing) its change output.\n"
            "If the change output is not big enough to cover the increased fee, the command will currently fail\n"
            "instead of adding new inputs to compensate. (A future implementation could improve this.)\n"
            "The command will fail if the wallet or mempool contains a transaction that spends one of T's outputs.\n"
            "By default, the new fee will be calculated automatically using estimatesmartfee.\n"
            "The user can specify a confirmation target for estimatesmartfee.\n"
            "Alternatively, the user can specify totalFee, or use RPC settxfee to set a higher fee rate.\n"
            "At a minimum, the new fee rate must be high enough to pay an additional new relay fee (incrementalfee\n"
            "returned by getnetworkinfo) to enter the node's mempool.\n"
            "\nArguments:\n"
            "1. txid                  (string, required) The txid to be bumped\n"
            "2. options               (object, optional)\n"
            "   {\n"
            "     \"confTarget\"        (numeric, optional) Confirmation target (in blocks)\n"
            "     \"totalFee\"          (numeric, optional) Total fee (NOT feerate) to pay, in satoshis.\n"
            "                         In rare cases, the actual fee paid might be slightly higher than the specified\n"
            "                         totalFee if the tx change output has to be removed because it is too close to\n"
            "                         the dust threshold.\n"
            "     \"replaceable\"       (boolean, optional, default true) Whether the new transaction should still be\n"