janky jenkins PR pipeline hack

gistfile1.txt

 isPR = env.BRANCH_NAME ? env.BRANCH_NAME.startsWith("PR-") : false
 if (isPR) {
     checkout scm:[$class: 'GitSCM', userRemoteConfigs: [[ url: repoURL, credentialsId: gitCredentialId ]]]
     sh "git fetch origin pull/'${numberPR}'/head:'${BRANCH_NAME}'"
     sh "git checkout '${BRANCH_NAME}'"
 } else {
     checkout scm:[$class: 'GitSCM', userRemoteConfigs: [[ url: repoURL, credentialsId: gitCredentialId ]]]
     sh 'git checkout master'
 }