merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/ci/test-documentation.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+#
+# Perform sanity checks on documentation and build it.
+#
+
+. ${0%/*}/lib.sh
+
+filter_log () {
+	sed -e '/^GIT_VERSION = /d' \
+	    -e '/^    \* new asciidoc flags$/d' \
+	    "$1"
+}
+
+make check-builtins
+make check-docs
+
+# Build docs with AsciiDoc
+make doc > >(tee stdout.log) 2> >(tee stderr.raw >&2)
+cat stderr.raw
+filter_log stderr.raw >stderr.log
+test ! -s stderr.log
+test -s Documentation/git.html
+test -s Documentation/git.xml
+test -s Documentation/git.1
+grep '<meta name="generator" content="AsciiDoc ' Documentation/git.html
+
+rm -f stdout.log stderr.log stderr.raw
+check_unignored_build_artifacts
+
+# Build docs with AsciiDoctor
+make clean
+make USE_ASCIIDOCTOR=1 doc > >(tee stdout.log) 2> >(tee stderr.raw >&2)
+cat stderr.raw
+filter_log stderr.raw >stderr.log
+test ! -s stderr.log
+test -s Documentation/git.html
+grep '<meta name="generator" content="Asciidoctor ' Documentation/git.html
+
+rm -f stdout.log stderr.log stderr.raw
+check_unignored_build_artifacts
+
+save_good_tree