master build broken in documentation tree

From the make install phase:

/bin/install -c -m 644 named.conf.5 /home/perflab/data/tests/5874cc7a252707aaa5c5f2b3/run/share/man/man5
/bin/xsltproc --novalid --xinclude --nonet -o named.8 ../../doc/xsl/isc-manpage.xsl named.docbook
Makefile:512: recipe for target 'named.8' failed
make[2]: Leaving directory '/home/perflab/data/tests/5874cc7a252707aaa5c5f2b3/build/bin/named'
Makefile:100: recipe for target 'install' failed
make[1]: Leaving directory '/home/perflab/data/tests/5874cc7a252707aaa5c5f2b3/build/bin'
Makefile:110: recipe for target 'install' failed

@ondrej suspects d9929b1b