This is an auto-filed bug because dev-ruby/tty-which fails tests. 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. NOTE: If you need further logs, feel free to ask.
Created attachment 640370 [details] build.log build log and emerge --info
This has been fixed in tty-which 0.4.2.