The BuildRequires: libxml2 line is missing from the sgml-common spec file.
Not from the one in rawhide since Nov 5th (0.6.3-6):
BuildRequires: libxml2 >= 2.4.8-2
Crapola. This is the SRPM that I downloaded and used, but RPM has been missing
buildrequires lately. This is the second SRPM that it's ignored buildrequires for.