RE: [PoC] pg_upgrade: allow to upgrade publisher node

Dear Hou,

Thank you for reviewing!

> 1.
>
>  #include "access/transam.h"
>  #include "catalog/pg_language_d.h"
> +#include "fe_utils/string_utils.h"
>  #include "pg_upgrade.h"
>
> It seems we don't need this head file anymore.

Removed.

> 2.
> +        if (*invalidated && SlotIsLogical(s) && IsBinaryUpgrade)
> +            elog(ERROR, "Replication slots must not be invalidated
> during the upgrade.");
>
> I think normally the first letter is lowercase, and we can avoid the period.

Right, fixed. Also, a period is removed based on the rule. Apart from other detailed
messages, this just reports what happened.

```
        if (nslots_on_old > max_replication_slots)
                pg_fatal("max_replication_slots (%d) must be greater than or equal to the number of "
-                                "logical replication slots (%d) on the old cluster.",
+                                "logical replication slots (%d) on the old cluster",
                                 max_replication_slots, nslots_on_old);
```

Best Regards,
Hayato Kuroda
FUJITSU LIMITED