Try to fix the travis pr id

.travis.yml

@@ -22,4 +22,4 @@ script:
   # file to see the specific configuration
   - curl -LsS https://binaries.sonarsource.com/Distribution/sonar-scanner-cli/sonar-scanner-cli-4.0.0.1744-linux.zip > sonar-scanner-cli-4.0.0.1744-linux.zip
   - unzip sonar-scanner-cli-4.0.0.1744-linux.zip
-  - sonar-scanner-4.0.0.1744-linux/bin/sonar-scanner -D sonar.branch.name=$TRAVIS_BRANCH -Dsonar.projectKey=jenkins-zh_jenkins-cli -Dsonar.organization=jenkins-zh -Dsonar.sources=. -Dsonar.host.url=https://sonarcloud.io -Dsonar.login=674e187e300edc0ad56a05705bd0b21cbe18bd52
+  - sonar-scanner-4.0.0.1744-linux/bin/sonar-scanner -D sonar.branch.name=$(if [ "$TRAVIS_PULL_REQUEST" == "false" ]; then echo $TRAVIS_BRANCH; else echo pr-$TRAVIS_PULL_REQUEST; fi) -Dsonar.projectKey=jenkins-zh_jenkins-cli -Dsonar.organization=jenkins-zh -Dsonar.sources=. -Dsonar.host.url=https://sonarcloud.io -Dsonar.login=674e187e300edc0ad56a05705bd0b21cbe18bd52