message: Attempt to fix occasional Linux CI failures.
  Remove old coverage build directories before building.
diff: @@ -56,7 +56,7 @@ def doDockerBuild(String flavor, Boolean withCoverage, Boolean enableSync) {
  sshagent(['realm-ci-ssh']) {
  image.inside("-v /etc/passwd:/etc/passwd:ro -v ${env.HOME}:${env.HOME} -v ${env.SSH_AUTH_SOCK}:${env.SSH_AUTH_SOCK} -e HOME=${env.HOME}") {
  if(withCoverage) {
  - sh "./workflow/test_coverage.sh ${sync} && mv coverage.build ${label}.build"
  + sh "rm -rf coverage.build ${label}.build && ./workflow/test_coverage.sh ${sync} && mv coverage.build ${label}.build"
  } else {
  sh "./workflow/build.sh ${flavor} ${sync}"
  }
  