Steps to reproduce: emerge nginx 1.7.2 with rtmp module.

Emerge fails with error:
./configure: error: no
/tmp/portage/www-servers/nginx-1.7.2/work/nginx-rtmp-module-v1.1.4/config was found

That path really doesn't exist. But that config is located at:
/tmp/portage/www-servers/nginx-1.7.2/work/nginx-rtmp-module-1.1.4/config

(there is no "v" before version number)