This is an auto-filled bug because dev-python/arpeggio 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 638578 [details] build.log build log and emerge --info
Fixed upstream, and fix included in current version in tree Fix in commit: https://github.com/textX/Arpeggio/commit/e432d7d0eda55772f128fe072c4922171631aa13