message: try to fix r test in travis
diff: @@ -11,6 +11,9 @@ before_script:
  - sudo -H pip3 install --upgrade setuptools wheel virtualenv
  - sudo -H pip3 install $TRAVIS_BUILD_DIR/emulator
  - sudo -H apt-get install r-base libxml2-dev
  + - sudo -H R --vanilla -e 'install.packages("stringi", dependencies=TRUE, INSTALL_opts = c("--no-lock"), repos="http://cran.us.r-project.org")'
  + - sudo -H R --vanilla -e 'install.packages("stringr", dependencies=TRUE, INSTALL_opts = c("--no-lock"), repos="http://cran.us.r-project.org")'
  + - sudo -H R --vanilla -e 'install.packages("glue", repos="http://cran.us.r-project.org")'
  - sudo -H R --vanilla -e 'install.packages("knitr", repos="http://cran.us.r-project.org")'
  - sudo -H R --vanilla -e 'install.packages("reticulate", repos="http://cran.us.r-project.org")'
  