converttopsbt given a funded tx produces a psbt that can't be signed

Create raw transaction

```
elements-cli createrawtransaction [] "{\"Azpsjg2XXT7phritvPLAv4PZM4QnCkCWHKiuA6jTWvW9CC91qwsvGJUD9rBPHNES5JSc5Hurqmh59Lko\":0.00001256}" 0 false "{\"Azpsjg2XXT7phritvPLAv4PZM4QnCkCWHKiuA6jTWvW9CC91qwsvGJUD9rBPHNES5JSc5Hurqmh59Lko\":\"b2e15d0d7a0c94e4e2ce0fe6e8691b9e451377f6e46e8045a86f7c4b5d4f0f23\"}"
0200000000000101230f4f5d4b7c6fa845806ee4f67713459e1b69e8e60fcee2e4940c7a0d5de1b20100000000000004e80343b01fc92b09d95c7917c1f1c28233dd7a1186d776703e6e6dd26732e20b44
```

Fund it

```
elements-cli fundrawtransaction 0200000000000101230f4f5d4b7c6fa845806ee4f67713459e1b69e8e60fcee2e4940c7a0d5de1b20100000000000004e80343b01fc92b09d95c7917c1f1c28233dd7a1186d776703e6e6dd26732e20b44e117a914800c73cf1b0788708b928fbae80c13cbdede5f788700000000
{
"hex": "020000000001c739fe40824f84fe84b7dc86f43d9f9956c04d1461baddf1033f595dd1367bc60000000000fdffffff0201230f4f5d4b7c6fa845806ee4f67713459e1b69e8e60fcee2e4940c7a0d5de1b20100000000000004e80343b01fc92b09d95c7917c1f1c28233dd7a1186d776703e6e6dd26732e20b44e117a914800c73cf1b0788708b928fbae80c13cbdede5f788701230f4f5d4b7c6fa845806ee4f67713459e1b69e8e60fcee2e4940c7a0d5de1b2010000000000000b59000000000000",
"fee": 0.00002905,
"changepos": -1
}
```
Convert it to a psbt

```

elements-cli converttopsbt 020000000001c739fe40824f84fe84b7dc86f43d9f9956c04d1461baddf1033f595dd1367bc60000000000fdffffff0201230f4f5d4b7c6fa845806ee4f67713459e1b69e8e60fcee2e4940c7a0d5de1b20100000000000004e80343b01fc92b09d95c7917c1f1c28233dd7a1186d776703e6e6dd26732e20b44e117a914800c73cf1b0788708b928fbae80c13cbdede5f788701230f4f5d4b7c6fa845806ee4f67713459e1b69e8e60fcee2e4940c7a0d5de1b2010000000000000b59000000000000
cHNldP8BAKMCAAAAAAHHOf5Agk+E/oS33Ib0PZ+ZVsBNFGG63fEDP1ld0TZ7xgAAAAAA/f///wIBIw9PXUt8b6hFgG7k9ncTRZ4baejmD87i5JQMeg1d4bIBAAAAAAAABOgAF6kUgAxzzxsHiHCLko+66AwTy97eX3iHASMPT11LfG+oRYBu5PZ3E0WeG2no5g/O4uSUDHoNXeGyAQAAAAAAAAtZAAAAAAAAAAAL/AhlbGVtZW50cwYhA0OwH8krCdlceRfB8cKCM916EYbXdnA+bm3SZzLiC0ThAAA=
```

Blind it

```
elements-cli blindpsbt cHNldP8BAKMCAAAAAAHHOf5Agk+E/oS33Ib0PZ+ZVsBNFGG63fEDP1ld0TZ7xgAAAAAA/f///wIBIw9PXUt8b6hFgG7k9ncTRZ4baejmD87i5JQMeg1d4bIBAAAAAAAABOgAF6kUgAxzzxsHiHCLko+66AwTy97eX3iHASMPT11LfG+oRYBu5PZ3E0WeG2no5g/O4uSUDHoNXeGyAQAAAAAAAAtZAAAAAAAAAAAL/AhlbGVtZW50cwYhA0OwH8krCdlceRfB8cKCM916EYbXdnA+bm3SZzLiC0ThAAA=
cHNldP8BAKMCAAAAAAHHOf5Agk+E/oS33Ib0PZ+ZVsBNFGG63fEDP1ld0TZ7xgAAAAAA/f///wIBIw9PXUt8b6hFgG7k9ncTRZ4baejmD87i5JQMeg1d4bIBAAAAAAAABOgAF6kUgAxzzxsHiHCLko+66AwTy97eX3iHASMPT11LfG+oRYBu5PZ3E0WeG2no5g/O4uSUDHoNXeGyAQAAAAAAAAtZAAAAAAAAAAAAAA==
```

Try to sign it:

```
elements-cli walletsignpsbt cHNldP8BAKMCAAAAAAHHOf5Agk+E/oS33Ib0PZ+ZVsBNFGG63fEDP1ld0TZ7xgAAAAAA/f///wIBIw9PXUt8b6hFgG7k9ncTRZ4baejmD87i5JQMeg1d4bIBAAAAAAAABOgAF6kUgAxzzxsHiHCLko+66AwTy97eX3iHASMPT11LfG+oRYBu5PZ3E0WeG2no5g/O4uSUDHoNXeGyAQAAAAAAAAtZAAAAAAAAAAAAAA==
error code: -25
error message:
Missing UTXOs that are needed to check transaction balance
```

Decode it:

```
elements-cli decodepsbt cHNldP8BAKMCAAAAAAHHOf5Agk+E/oS33Ib0PZ+ZVsBNFGG63fEDP1ld0TZ7xgAAAAAA/f///wIBIw9PXUt8b6hFgG7k9ncTRZ4baejmD87i5JQMeg1d4bIBAAAAAAAABOgAF6kUgAxzzxsHiHCLko+66AwTy97eX3iHASMPT11LfG+oRYBu5PZ3E0WeG2no5g/O4uSUDHoNXeGyAQAAAAAAAAtZAAAAAAAAAAAAAA==
{
"tx": {
"txid": "58f50ab2318eeb6d7247de5d74f6e2b43a1a6d504ad09fd37a58d23c06876a4b",
"hash": "58f50ab2318eeb6d7247de5d74f6e2b43a1a6d504ad09fd37a58d23c06876a4b",
"wtxid": "58f50ab2318eeb6d7247de5d74f6e2b43a1a6d504ad09fd37a58d23c06876a4b",
"withash": "f150819cebd18e742bd70158fbf154dc6ca75b445141c87e8492bf48b758e628",
"version": 2,
"size": 163,
"vsize": 163,
"weight": 652,
"locktime": 0,
"vin": [
{
"txid": "c67b36d15d593f03f1ddba61144dc056999f3df486dcb784fe844f8240fe39c7",
"vout": 0,
"scriptSig": {
"asm": "",
"hex": ""
},
"is_pegin": false,
"sequence": 4294967293
}
],
"vout": [
{
"value": 0.00001256,
"asset": "b2e15d0d7a0c94e4e2ce0fe6e8691b9e451377f6e46e8045a86f7c4b5d4f0f23",
"commitmentnonce": "",
"commitmentnonce_fully_valid": false,
"n": 0,
"scriptPubKey": {
"asm": "OP_HASH160 800c73cf1b0788708b928fbae80c13cbdede5f78 OP_EQUAL",
"hex": "a914800c73cf1b0788708b928fbae80c13cbdede5f7887",
"reqSigs": 1,
"type": "scripthash",
"addresses": [
"XP2JFuUmgaeMfCqHazL2WtsKhp9fVhondp"
]
}
},
{
"value": 0.00002905,
"asset": "b2e15d0d7a0c94e4e2ce0fe6e8691b9e451377f6e46e8045a86f7c4b5d4f0f23",
"commitmentnonce": "",
"commitmentnonce_fully_valid": false,
"n": 1,
"scriptPubKey": {
"asm": "",
"hex": "",
"type": "fee"
}
}
]
},
"fees": {
"bitcoin": 0.00002905
},
"unknown": {
},
"inputs": [
{
}
],
"outputs": [
{
},
{
}
]
}
```