You have to provide the following information whenever possible.

**Describe the bug**
This query fails with the latest stable version 21.5.5.12. It worked with the last stable version 21.4.7.3.

**Does it reproduce on recent release?**
yes

**How to reproduce**
21.5.5.12

```
SELECT
    label,
    number
FROM
(
    SELECT
        'a' AS label,
        number
    FROM
    (
        SELECT number
        FROM numbers(10)
    )
    UNION ALL
    SELECT
        'b' AS label,
        number
    FROM
    (
        SELECT number
        FROM numbers(10)
    )
)
WHERE number IN
(
    SELECT number
    FROM numbers(5)
)
```

**Expected behavior**
Query should run without errors

**Error message and/or stacktrace**
```
Received exception from server (version 21.5.5):
Code: 49. DB::Exception: Received from localhost:9000. DB::Exception: Block structure mismatch in Pipe::unitePipes stream: different names of columns:
label String String(size = 0), number UInt64 UInt64(size = 0), 'b' String Const(size = 0, String(size = 1))
label String String(size = 0), number UInt64 UInt64(size = 0), 'a' String Const(size = 0, String(size = 1)).
```

out << "ARRAY JOIN ";
                break;
            case ActionsDAG::ActionType::INPUT:
                out << "INPUT ";
                break;
        }
        out << "(";
        for (size_t i = 0; i < node.children.size(); ++i)
        {
            if (i)
                out << ", ";
            out << map[node.children[i]];
        }
        out << ")";
        out << " " << (node.column ? node.column->getName() : "(no column)");
        out << " " << (node.result_type ? node.result_type->getName() : "(no type)");
        out << " " << (!node.result_name.empty() ? node.result_name : "(no name)");
        if (node.function_base)
            out << " [" << node.function_base->getName() << "]";
        if (node.is_function_compiled)
            out << " [compiled]";
        out << "\n";
    }
    out << "Index:";
    for (const auto * node : index)
        out << ' ' << map[node];
    out << '\n';
    return out.str();
}
bool ActionsDAG::hasArrayJoin() const