[tlbuild] Spurious warning about insufficient disk space

[Karl Berry]

    % echo $BLOCKSIZE
    1k

Oh. Well, that will do it. I was unaware of that envvar. Can I set
BLOCKSIZE=512 (or something else) to get 512-byte blocks? Or do I have
to unset BLOCKSIZE?

    By the way, POSIXLY_CORRECT has no effect with NetBSD df.

Sure, I know, but it's necessary for GNU df (at least).

    Wouldn't it be better to use df -Pk, which should work properly

Maybe so. I hadn't realized -k was mandated by POSIX, but I guess it is.

It would not surprise me if a df fails to implement the combination of
-Pk properly. But I guess we could try it. I agree, could be
better. Done in r66112.

    on most (if not all)?

Yours was the first report of failure on what we do now ... --thanks, karl.