This is an auto-filled bug because app-admin/cygwin-rebase fails to compile. 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 637080 [details] build.log build log and emerge --info
Well, KEYWORDS="-*" is there for a reason, as it is a Cygwin only package. Not sure who/what does find this package to build for Linux.
sorry I didn't see it