Lennart Poettering is 'famous' for creating pulseaudio stack, here is a commit from his latest 'art' named systemd.
COMMIT: http://cgit.freedesktop.org/systemd/commit/?id=80758717a6359cbe6048f43a17c2b53a3ca8c2fa
Code:
+ log_warning("[color="Red"]/usr appears to be on a different file system than /. This is not supported anymore.[/color] "
+ "Some things will probably break (sometimes even silently) in mysterious ways.");
COMMIT: http://cgit.freedesktop.org/systemd/commit/?id=80758717a6359cbe6048f43a17c2b53a3ca8c2fa