It occurred to me that Martti Kuparinen wrote in gmane.os.netbsd.devel.packages:
> Hi!
>
> Any ideas what this is...
[...]
> pax: Trying to read GNU tar archive with extensions off
> pax: Trying to read GNU tar archive with extensions off

No, but I'm seeing it too (-current, about a week old). It's preventing
me from updating firefox..