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)).
```

Node node;
                node.type = ActionType::COLUMN;
                node.result_name = predicate->result_type->getName();
                node.column = DataTypeString().createColumnConst(0, node.result_name);
                node.result_type = std::make_shared<DataTypeString>();
                const auto * right_arg = &nodes.emplace_back(std::move(node));
                const auto * left_arg = new_children.front();
                predicate->children = {left_arg, right_arg};
                auto arguments = prepareFunctionArguments(predicate->children);
                FunctionOverloadResolverPtr func_builder_cast = CastOverloadResolver<CastType::nonAccurate>::createImpl(false);
                predicate->function_builder = func_builder_cast;
                predicate->function_base = predicate->function_builder->build(arguments);
                predicate->function = predicate->function_base->prepare(arguments);
            }
        }
        else
        {
            
            
            predicate->children.swap(new_children);
            auto arguments = prepareFunctionArguments(predicate->children);
            predicate->function_base = predicate->function_builder->build(arguments);
            predicate->function = predicate->function_base->prepare(arguments);
        }
        removeUnusedActions(false);
    }
    return actions;
}
}