A couple of paragraphs in I started wondering if it was going to turn out to be systemd-tmpfiles (in ubuntu, 16.04 I think? The symptom was "about 10 days after

A couple of paragraphs in I started wondering if it was going to turn out to be systemd-tmpfiles (in ubuntu, 16.04 I think? The symptom was "about 10 days after login, X11 forwarding over ssh stopped working but local apps could still open windows just fine." I remember it as an ubuntu-specific misconfiguration, though I think the systemd defaults were changed to be less of a footgun in response...) I was pleased that it was more interesting than that, and I want people to write more twitchy-detail-post-mortems like this :-)