FreeBSD web build failed on build-web.ysv.freebsd.org

[User Www-data]

===> ../../ja_JP.eucJP/htdocs/doc
Warning: Object directory not changed from original /usr/local/www/build/head/ja_JP.eucJP
===> ../../ja_JP.eucJP/htdocs/doc/articles (all)
Warning: Object directory not changed from original /usr/local/www/build/head/ja_JP.eucJP/articles
===> ../../ja_JP.eucJP/htdocs/doc/articles/contributing (all)
Warning: Object directory not changed from original /usr/local/www/build/head/ja_JP.eucJP/articles/contributing
===> ../../ja_JP.eucJP/htdocs/doc/articles/contributors (all)
Warning: Object directory not changed from original /usr/local/www/build/head/ja_JP.eucJP/articles/contributors
===> ../../ja_JP.eucJP/htdocs/doc/articles/fonts (all)
Warning: Object directory not changed from original /usr/local/www/build/head/ja_JP.eucJP/articles/fonts
===> ../../ja_JP.eucJP/htdocs/doc/articles/ipsec-must (all)
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===> ../../ja_JP.eucJP/htdocs/doc/articles/leap-seconds (all)
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===> ../../ja_JP.eucJP/htdocs/doc/articles/problem-reports (all)
Warning: Object directory not changed from original /usr/local/www/build/head/ja_JP.eucJP/articles/problem-reports
===> ../../ja_JP.eucJP/htdocs/doc/books (all)
Warning: Object directory not changed from original /usr/local/www/build/head/ja_JP.eucJP/books
===> ../../ja_JP.eucJP/htdocs/doc/books/design-44bsd (all)
Warning: Object directory not changed from original /usr/local/www/build/head/ja_JP.eucJP/books/design-44bsd
===> ../../ja_JP.eucJP/htdocs/doc/books/faq (all)
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===> ../../ja_JP.eucJP/htdocs/doc/books/handbook (all)
env XML_CATALOG_FILES="file:///usr/local/www/build/head/ja_JP.eucJP/books/handbook/catalog-cwd.xml  file:///usr/local/www/build/head/ja_JP.eucJP/share/xml/catalog.xml  file:///usr/local/www/build/head/share/xml/catalog.xml  file:///usr/local/share/xml/catalog" /usr/local/bin/xmllint --nonet --noent --valid --dropdtd --xinclude /usr/local/www/build/head/ja_JP.eucJP/books/handbook/book.xml > book.parsed.xml.tmp
/usr/local/www/build/head/ja_JP.eucJP/books/handbook/book.xml:937: element link: validity error : IDREF attribute linkend references an unknown ID "stable"
*** Error code 4

Stop.
make[5]: stopped in /usr/local/www/build/head/ja_JP.eucJP/books/handbook
*** Error code 1

Stop.
make[4]: stopped in /usr/local/www/build/head/ja_JP.eucJP/books
*** Error code 1

Stop.
make[3]: stopped in /usr/local/www/build/head/ja_JP.eucJP
*** Error code 1

Stop.
make[2]: stopped in /usr/local/www/build/head/ja_JP.eucJP/htdocs/doc
*** Error code 1

Stop.
make[1]: stopped in /usr/local/www/build/head/ja_JP.eucJP/htdocs
*** Error code 1

Stop.
make: stopped in /usr/local/www/build/head/en_US.ISO8859-1/htdocs
       66.25 real        47.75 user        20.58 sys