June 11th, 2018 R 3.5.0 on Debian and Ubuntu: An Update

Overview R 3.5.0 was released a few weeks ago. As it changes some (important) internals, packages installed with a previous version of R have to be rebuilt. This was known and expected, and we took several measured steps to get R binaries to everybody without breakage. The question of but how do I upgrade without breaking my system was asked a few times, e.g., on the r-sig-debian list as well as in this StackOverflow question.