Build failed in Jenkins: Build-UFS-image #2718

See <https://jenkins.FreeBSD.org/job/Build-UFS-image/2718/>

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Started by upstream project "Build_Image_and_Run_Tests_in_Bhyve_HEAD" build number 1758
originally caused by:
 Started by upstream project "FreeBSD_HEAD" build number 3516
 originally caused by:
  Started by an SCM change
Building remotely on jenkins-10.freebsd.org (FreeBSD-10)No JDK named ?null? found
 in workspace <https://jenkins.FreeBSD.org/job/Build-UFS-image/ws/>
No JDK named ?null? found
No JDK named ?null? found
 > git rev-parse --is-inside-work-tree # timeout=10
Fetching changes from the remote Git repository
 > git config remote.origin.url https://github.com/freebsd/freebsd-ci # timeout=10
Fetching upstream changes from https://github.com/freebsd/freebsd-ci
 > git --version # timeout=10
 > git -c core.askpass=true fetch --tags --progress https://github.com/freebsd/freebsd-ci +refs/heads/*:refs/remotes/origin/*
 > git rev-parse refs/remotes/origin/master^{commit} # timeout=10
 > git rev-parse refs/remotes/origin/origin/master^{commit} # timeout=10
Checking out Revision 65a323ece2701c4a650ed241aea8bdecfaf56ea9 (refs/remotes/origin/master)
No JDK named ?null? found
 > git config core.sparsecheckout # timeout=10
 > git checkout -f 65a323ece2701c4a650ed241aea8bdecfaf56ea9
 > git rev-list 65a323ece2701c4a650ed241aea8bdecfaf56ea9 # timeout=10
No JDK named ?null? found
[Build-UFS-image] $ /bin/sh -xe /tmp/hudson887574467276929336.sh
+ freebsd-ci/scripts/build/build-ufs-image.sh
+ [ -z <https://jenkins.FreeBSD.org/job/Build-UFS-image/ws/> ]
+ [ -z /builds/FreeBSD_HEAD ]
+ [ -z '' ]
+ export MAKEOBJDIRPREFIX=/builds/FreeBSD_HEAD/obj
+ [ -z '' ]
+ basename /builds/FreeBSD_HEAD
+ PACKAGE_ROOT=<https://jenkins.FreeBSD.org/job/Build-UFS-image/ws/package/FreeBSD_HEAD>
+ [ -z '' ]
+ basename /builds/FreeBSD_HEAD
+ IMAGE_ROOT=<https://jenkins.FreeBSD.org/job/Build-UFS-image/ws/image/FreeBSD_HEAD>
+ [ -n '' ]
+ [ -z /builds/FreeBSD_HEAD/obj ]
+ cd /builds/FreeBSD_HEAD
+ [ -z '' ]
+ [ -f /builds/FreeBSD_HEAD/make.conf ]
+ __MAKE_CONF=/builds/FreeBSD_HEAD/make.conf
+ sudo rm -fr <https://jenkins.FreeBSD.org/job/Build-UFS-image/ws/package/FreeBSD_HEAD>
rm: <https://jenkins.FreeBSD.org/job/Build-UFS-image/ws/package/FreeBSD_HEAD/var/empty>: Operation not permitted
rm: <https://jenkins.FreeBSD.org/job/Build-UFS-image/ws/package/FreeBSD_HEAD/var>: Directory not empty
rm: <https://jenkins.FreeBSD.org/job/Build-UFS-image/ws/package/FreeBSD_HEAD>: Directory not empty
Build step 'Execute shell' marked build as failure
No JDK named ?null? found