Jenkins - Get last completed build status
Solution 1:
Try http://$host/job/$jobname/lastSuccessfulBuild/api/json
Jenkins (and Hudson) expose multiple different builds, such as lastBuild, lastStableBuild, lastSuccessfulBuild, lastFailedBuild, lastUnstableBuild, lastUnsuccessfulBuild, lastCompletedBuild.
Solution 2:
To get the last successful build number:
curl --user <userName:password> https://<url>/job/<job-Name>/api/xml?xpath=/*/lastSuccessfulBuild/number