Re: `@need` badly influences top margin

[Werner LEMBERG]

>> Alas, it doesn't work well.  It seems that `@need` now
>> unconditionally inserts vertical space if not at a page break; see
>> attached example.
> 
> I've committed a fix to hide this negative skip with a penalty.
> With this fix, @need does make a very small effect on the page
> spacing, with it being tigher without, although I didn't investigate
> why.  (I suspect a pair of glue immediately followed by negative
> glue of the same magnitude has a suppressive effect on overall page
> stretch due to stretch in this pair being accounted for.)

Works now, thanks.

It seems that this slightly increased vertical spacing not only
affects explicit `@need` calls but also implicit ones that
`texinfo.tex` inserts by itself, for example, after a `@subsection`
command.  At least I observe that now a subsection (without any
explicit `@need`) that could fit previously on a page – together with
a directly following three-line paragraph – now starts on the next
page.

> This breaks the output from your footnote test case, though - I
> don't know why.  All I can suggest there is using a larger value,
> e.g.  @need 1500.

For my real-world case my previous `@need` value works as expected.


    Werner