Not really a bug, just to note that mpost is build during install phase, instead of compile.
Thanks. Could you attach the _relevant_ part of emerge output, and your emerge --info just in case? :)
Created attachment 137706 [details] relevant lines of emerge log I think emerge --info is irrelevant here. Log won't tell you much, but if you want it... These are the lines printed during install, those of mpost plus a few for context.
fixed, thanks for reporting