fix linux artifact build

tools/internal_ci/helper_scripts/prepare_build_macos_rc

@@ -31,7 +31,7 @@ brew install gflags
 
 set +ex  # rvm script is very verbose and exits with errorcode
 source $HOME/.rvm/scripts/rvm
-set -e  # rvm commands are very verbose  
+set -e  # rvm commands are very verbose
 rvm install ruby-2.4
 rvm osx-ssl-certs status all
 rvm osx-ssl-certs update all

tools/internal_ci/linux/grpc_build_artifacts.sh

@@ -22,6 +22,7 @@ source tools/internal_ci/helper_scripts/prepare_build_linux_rc
 
 # TODO(jtattermusch): install ruby on the internal_ci worker
 gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
-curl -sSL https://get.rvm.io | bash -s stable --ruby
+# TODO(jtattermusch): grep works around https://github.com/rvm/rvm/issues/4068
+curl -sSL https://get.rvm.io | grep -v __rvm_print_headline | bash -s stable --ruby
 
 tools/run_tests/task_runner.py -f artifact linux