dev-lang/swi-prolog-5.6.49 has been in the tree for over 30 days without any reported bugs. Please stabilize.
ppc stable
Fails test on x86 (and probably others) without USE=zlib. Try it yourself. Maybe RESTRICT="!zlib? ( test )" is needed here.
x86 stable
Thanks for catching that Christian; I've disabled just the rdf_zlib_plugin tests when the zlib4pl package is not built.
alpha/sparc stable
amd64 stable. Closing.