This is an auto-filled bug because app-misc/carbon-c-relay calls commands that do not exist. The issue was originally discovered on amd64, but it may be reproducible on other arches as well. If you think that a different summary clarifies the issue better, feel free to change it. Attached build log and emerge --info.
Created attachment 638044 [details] build.log build log and emerge --info
this is intended behaviour of upstream, and not harmful