Reported by @kallewoof here: https://github.com/bitcoin/bitcoin/pull/13917#issuecomment-412459298

```
$ ./bitcoin-cli createpsbt "[]" "[{\"$(./bitcoin-cli getnewaddress)\":0.01}]"
cHNidP8BACoCAAAAAAFAQg8AAAAAABepFG6Rty1Vk+fUOR4v9E6R6YXDFkHwhwAAAAAAAA==
$ ./bitcoin-cli decodepsbt cHNidP8BACoCAAAAAAFAQg8AAAAAABepFG6Rty1Vk+fUOR4v9E6R6YXDFkHwhwAAAAAAAA==
error code: -22
error message:
TX decode failed CDataStream::read(): end of data: unspecified iostream_category error
```

{
        vch.erase(vch.begin(), vch.begin() + nReadPos);
        nReadPos = 0;
    }
    bool Rewind(size_type n)
    {
        
        if (n > nReadPos)
            return false;
        nReadPos -= n;
        return true;
    }
    
    
    
    bool eof() const             { return size() == 0; }