message: Fix reference branch name in build script
diff: @@ -360,7 +360,7 @@ pipeline {
  ])
  sshagent(['84d71a75-cbb6-489a-8f4c-d0e2793201e9']) {
  sh """
  - if [ "${env.GIT_BRANCH}" = "origin/master" ]; then
  + if [ "${env.GIT_BRANCH}" = "master" ]; then
  rsync -e "ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null" -r -z --delete build/doc/html/ www.inet.haw-hamburg.de:/users/www/www.actor-framework.org/html/doc
  scp -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null build/doc/manual.pdf www.inet.haw-hamburg.de:/users/www/www.actor-framework.org/html/pdf/manual.pdf
  fi
  @@ -373,7 +373,7 @@ pipeline {
  url: 'git@github.com:actor-framework/read-the-docs.git',
  ])
  sh """
  - if [ "${env.GIT_BRANCH}" = "origin/master" ]; then
  + if [ "${env.GIT_BRANCH}" = "master" ]; then
  cp ../caf-sources/build/doc/rst/* .
  if [ -n "\$(git status --porcelain)" ]; then
  git add .
  