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)).
```

if (conjunction.size() > 1)
    {
        NodeRawConstPtrs args;
        args.reserve(conjunction.size());
        for (const auto * predicate : conjunction)
            args.emplace_back(nodes_mapping[predicate]);
        result_predicate = &actions->addFunction(func_builder_and, std::move(args), {});
    }
    actions->index.push_back(result_predicate);
    for (const auto & col : all_inputs)
    {
        const Node * input;
        auto & list = required_inputs[col.name];
        if (list.empty())
            input = &actions->addInput(col);
        else
        {
            input = list.front();
            list.pop_front();
            actions->inputs.push_back(input);
        }
        actions->index.push_back(input);
    }
    return actions;
}
ActionsDAGPtr ActionsDAG::cloneActionsForFilterPushDown(
    const std::string & filter_name,
    bool can_remove_filter,
    const Names & available_inputs,
    const ColumnsWithTypeAndName & all_inputs)