fix prev link in docs

[Nathan Bossart]

Right now, if you go to the following page and click "Prev", it'll send you
to the middle of the previous chapter:

        https://www.postgresql.org/docs/devel/bgworker.html

My research indicates that this might caused by a bug in libxml2, but
regardless, a minimal fix is to change the link generation code to use
[position()=last()] instead of [last()] in the predicate on the union of
reverse axes.  Patch attached.

-- 
nathan

>From b874600ab6df9252b04ea4b9d98ece2e1f917850 Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nat...@postgresql.org>
Date: Wed, 10 Jun 2026 14:14:45 -0500
Subject: [PATCH v1 1/1] fix prev link in docs

---
 doc/src/sgml/stylesheet-speedup-xhtml.xsl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/src/sgml/stylesheet-speedup-xhtml.xsl 
b/doc/src/sgml/stylesheet-speedup-xhtml.xsl
index da0f2b5a970..a3b3692ba03 100644
--- a/doc/src/sgml/stylesheet-speedup-xhtml.xsl
+++ b/doc/src/sgml/stylesheet-speedup-xhtml.xsl
@@ -208,7 +208,7 @@
              |ancestor::article[1]
              |ancestor::topic[1]
              |preceding::sect1[1]
-             |ancestor::sect1[1])[last()]"/>
+             |ancestor::sect1[1])[position()=last()]"/>
 
   <xsl:variable name="next"
     select="(following::book[1]
-- 
2.50.1 (Apple Git-155)