Editing the wiki page with non-Latin characters using webinterface also fails with the same error.
Additionally, embedding graphviz graphs non-Latin, leads to he same error.
Observed in ikiwiki versions 3.20130904 and version 3.20140102
+
+> This is probably [[fixed|done]] in 3.20140916. Please provide more
+> information if not. --[[smcv]]