It looks like multiple workers in the amplab jenkins cannot execute lsof. Example log below:
spark-build/dev/create-release/release-build.sh: line 344: lsof: command not found
usage: kill [ -s signal | -p ] [ -a ] pid ...
kill -l [ signal ]
I looked at the jobs and it looks like only amp-jenkins-worker-01 works so you are getting a successful build every week or so. Unclear if the snapshot is actually released.