The most simple to understand the issue is to run nginx -V Look for --user in output. I have it in the last line, it look so: --without-mail_imap_module --without-mail_pop3_module --without-mail_smtp_module --user='nginx --group=nginx' Nota bene at --user= value. There are two ' missed. Because of the issue we have no working nginx without "user" value set in config-file getting the error: nginx: [emerg] getpwnam("nginx --group=nginx") failed. I think it should be fixed in the myconf+=( --user=${PN}" "--group=${PN} ) part of the ebuild but I can't clearly get how.
Good catch, I am working on this.
Fix is part of https://github.com/gentoo/gentoo/pull/1920
Fix landed in the repository: https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=3f6a2bd81eb91481c2ccc0914773410e97c02e0d Again, thanks for the report!