Merge branch 'bc/doc-use-docbook-5'

Start using DocBook 5 (instead of DocBook 4.5) as Asciidoctor 2.0
no longer works with the older one.

* bc/doc-use-docbook-5:
  Documentation: fix build with Asciidoctor 2

Author: gitster

Documentation/Makefile

@@ -198,11 +198,13 @@ ifdef USE_ASCIIDOCTOR
 ASCIIDOC = asciidoctor
 ASCIIDOC_CONF =
 ASCIIDOC_HTML = xhtml5
-ASCIIDOC_DOCBOOK = docbook45
+ASCIIDOC_DOCBOOK = docbook5
 ASCIIDOC_EXTRA += -acompat-mode -atabsize=8
 ASCIIDOC_EXTRA += -I. -rasciidoctor-extensions
 ASCIIDOC_EXTRA += -alitdd='&\#x2d;&\#x2d;'
 DBLATEX_COMMON =
+XMLTO_EXTRA += --skip-validation
+XMLTO_EXTRA += -x manpage.xsl
 endif
 
 SHELL_PATH ?= $(SHELL)

Documentation/manpage.xsl

@@ -0,0 +1,3 @@
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
+	<xsl:import href="http://docbook.sourceforge.net/release/xsl-ns/current/manpages/docbook.xsl" />
+</xsl:stylesheet>

azure-pipelines.yml

@@ -374,7 +374,7 @@ jobs:
        test "$GITFILESHAREPWD" = '$(gitfileshare.pwd)' || ci/mount-fileshare.sh //gitfileshare.file.core.windows.net/test-cache gitfileshare "$GITFILESHAREPWD" "$HOME/test-cache" || exit 1
 
        sudo apt-get update &&
-       sudo apt-get install -y asciidoc xmlto asciidoctor &&
+       sudo apt-get install -y asciidoc xmlto asciidoctor docbook-xsl-ns &&
 
        export ALREADY_HAVE_ASCIIDOCTOR=yes. &&
        export jobname=Documentation &&

ci/install-dependencies.sh

@@ -53,7 +53,7 @@ StaticAnalysis)
 	;;
 Documentation)
 	sudo apt-get -q update
-	sudo apt-get -q -y install asciidoc xmlto
+	sudo apt-get -q -y install asciidoc xmlto docbook-xsl-ns
 
 	test -n "$ALREADY_HAVE_ASCIIDOCTOR" ||
 	gem install --version 1.5.8 asciidoctor

ci/test-documentation.sh

@@ -8,6 +8,8 @@
 filter_log () {
 	sed -e '/^GIT_VERSION = /d' \
 	    -e '/^    \* new asciidoc flags$/d' \
+	    -e '/stripped namespace before processing/d' \
+	    -e '/Attributed.*IDs for element/d' \
 	    "$1"
 }