system-config-printer fails while validating doc.

[fede2cr]

xmlto man -o man man/system-config-printer.xml
xmlto: /tmp/system-config-printer-1.5.11/man/system-config-printer.xml does not validate (status 3)
xmlto: Fix document syntax or use --skip-validation option
I/O error : Attempt to load network entity http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
/tmp/system-config-printer-1.5.11/man/system-config-printer.xml:3: warning: failed to load external entity "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">
^
I/O error : Attempt to load network entity http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
warning: failed to load external entity "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"
validity error : Could not load the external subset "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"
Document /tmp/system-config-printer-1.5.11/man/system-config-printer.xml does not validate
make[1]: *** [Makefile:2020: .stamp-man-pages-built] Error 13
make[1]: Leaving directory '/tmp/system-config-printer-1.5.11'