Ubuntu finally released a kernel update (4.4.0-93) that fixes the regression that broke rr. It took a month after the regression was fixed upstream. The slow update cycle has been frustrating, and it's a bit worrying: I hope security fixes are treated with more urgency!
Fedora updated F25 last week (updating to a 4.12 kernel) and F26 was fixed earlier, so I think we're mostly out of the woods on this issue. I will prepare an rr 4.6.0 release.