The command "sudo add-apt-repository -y "ppa:marutter/rrutter4.0"" failed and exited with 1

Hi there @jeroen, @jimhester

My Travis test fails at the very first step in Linux when trying to install R.

> Installing R
$ sudo add-apt-repository -y "ppa:marutter/rrutter4.0"
Error: retrieving gpg key timed out.
The command "sudo add-apt-repository -y "ppa:marutter/rrutter4.0"" failed and exited with 1 during .

I added dist: bionic to my .travis.yml after reading this post Build can't find r-cran-xxx binaries but that did not really seem to help.
My config is the following:

language: r
dist: bionic
sudo: false
cache: packages

r:
  - release

r_packages:
  - nlme
  - devtools

# to avoid building vignettes which takes too long
r_check_args: "--no-build-vignettes --ignore-vignettes"
r_build_args: "--no-build-vignettes --ignore-vignettes"

addons:
  apt:
    packages:
      - libmagick++-dev

warnings_are_errors: true

os:
  - linux
  - osx
pandoc: true

Find the failing test here

All and any help is appreciated!

I have found how this seems to be a transient problem with the Travis Linus servers when they get overloaded. Sorry for the duplicate!

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