Easy to reproduce:
### 20.3.13
```
SELECT 1
FORMAT JSON

{
        "meta":
        [
                {
                        "name": "1",
                        "type": "UInt8"
                }
        ],

        "data":
        [
                {
                        "1": 1
                }
        ],

        "rows": 1,

        "statistics":
        {
                "elapsed": 0.000203731,
                "rows_read": 1,
                "bytes_read": 1
        }
}
```

### 20.4.5
```
:) select 1 format JSON

SELECT 1
FORMAT JSON

{
        "meta":
        [
                {
                        "name": "1",
                        "type": "UInt8"
                }
        ],

        "data":
        [
                {
                        "1": 1
>>>>>>>> no closing bracket <<<<<<<<<<
        ],

        "rows": 1,

        "statistics":
        {
                "elapsed": 0.000771732,
                "rows_read": 1,
                "bytes_read": 1
        }
}
```
### master
```

SELECT 1
FORMAT JSON

{
        "meta":
        [
                {
                        "name": "1",
                        "type": "UInt8"
                }
        ],

        "data":
        [
                {
                        "1": 1
>>>>>>>> no closing bracket <<<<<<<<<<
        ],

        "rows": 1,

        "statistics":
        {
                "elapsed": 0.00103364,
                "rows_read": 1,
                "bytes_read": 1
        }
}

```

{
            // Read until separator.
            hile (!in.eof())
            {
                char * next_separator = find_first_symbols<''>(in.position(),
                    in.buffer().end())
                if (next_separator < in.buffer().end())
                {
                    next_separator++
                    if (next_separator < in.buffer().end()
                        && *next_separator == '\n')
                    {
                        // Found '\n', append it to the query text and try to
                        // parse.
                        next_separator++
                        text.append(in.position(), next_separator - in.position())
                        in.position() = next_separator
                        break
                    
                
                // Didn't find the semicolon and reached the end of buffer.
                text.append(in.position(), next_separator - in.position())
                in.position() = next_separator
                if (text.size() > 1024 * 1024)
                {
                    // We've read a lot of text and still haven't seen a separator.
                    // Likely some pathologil input, just fall through to prevent
                    // too long loops.
                    break