Due to an underspecified Makefile target prerequisite, a parallel make of app-misc/screen can fail in this way: cp ./utf8encodings/?? /var/tmp/portage/app-misc/screen-4.5.1/image//usr/share/screen/utf8encodings cp: target '/var/tmp/portage/app-misc/screen-4.5.1/image//usr/share/screen/utf8encodings' is not a directory make: *** [Makefile:92: install_bin] Error 1 make: *** Waiting for unfinished jobs.... mkdir /var/tmp/portage/app-misc/screen-4.5.1/image//usr/share/screen mkdir /var/tmp/portage/app-misc/screen-4.5.1/image//usr/share/screen/utf8encodings This occurs because the "install_bin" Makefile target does not directly require the "installdirs" target. The "install" target requires "installdirs install_bin", but this does not guarantee that "installdirs" will complete before "install_bin" begins. A solution is to add "installdirs" as a prerequisite of the "install_bin" target.
Created attachment 465436 [details, diff] ebuild patch that fixes the Makefile
Thanks for submitting your patch directly to upstream. This was included in screen-4.6.1.