Edge case with dbfo-need

[Richard Hamilton <hamilton@xmlpress.net>]

I just ran into an interesting edge case when building with dbfo-need when the following conditions are true:

1) You have a dbfo-need processing instruction above an admonition (warning, tip, etc.)
2) The admonition is the last element in a section (technically, the last block element; an indexterm doesn't change anything).
3) The dbfo-need is not activated (that is, the admonition is small enough to fit on the current page).

When these three things are true, the vertical space between the preceding paragraph and the admonition will be smaller if there is a dbfo-need than if the processing instruction is not present.

I was running the 1.78.1 stylesheets (as well as a more recent snapshot) with no customization, Saxon, and XEP. I don't have a version of FOP active, so I don't know if this is a problem with XEP, the stylesheets, or something else.

I've included a short example that illustrates the problem.

Does anyone have any idea what might be going on here?

Best regards,
Dick Hamilton
-------
XML Press
XML for Technical Communicators
http://xmlpress.net
hamilton@xmlpress.net

================ Sample docbook =================

<?xml version="1.0" encoding="utf-8"?>
<article xmlns="http://docbook.org/ns/docbook"; version="5.0">
  <title>dbfo-need and admonition example</title>
  <section xml:id="s.shorthistory">
    <title>First section</title>
    <para>This first admonition has a dbfo-need processing instruction in front of it.</para>
    <?dbfo-need height="1in"?>
    <warning>
      <para>This one has a dbfo-need in front of it.</para>
    </warning>
  </section>
  <section>
    <title>Second section</title>
    <para>This admonition does not have a dbfo-need processing instruction in front of it.</para>
    <warning>
      <para>This one has no dbfo-need in front of it.</para>
    </warning>
  </section>
</article>