The latter page still exists for me; the former is deleted. The issue in current OpenSuse 42.2 is that under some circumstances, the contents of theorem environments are not typeset in italics, although they should. Do you need an MWE or are you aware of the issue? The patch would essentially have to bring fontspec to version 2.6 or later (or repair the definition of \emph in an older fontspec version). If you could really do that, I'd be very thankful.