clean up zombie procs before starting integration tests

hack/jenkins/common.sh

@@ -125,6 +125,18 @@ for stale_dir in ${TEST_ROOT}/*; do
   rmdir "${stale_dir}" || true
 done
 
+
+# sometimes tests left over zombie procs that won't exit
+# for example:
+# jenkins  20041  0.0  0.0      0     0 ?        Z    Aug19   0:00 [minikube-linux-] <defunct>
+zombie_defuncts=$(ps -A -ostat,ppid | awk '/[zZ]/ && !a[$2]++ {print $2}C')
+if [[ "${zombie_defuncts}" != "" ]]; then
+  echo "Found zombie defunct procs to kill..."
+  ps -f -p ${kprocs} || true
+  sudo -E kill ${kprocs} || true
+fi
+
+
 if type -P virsh; then
   virsh -c qemu:///system list --all
   virsh -c qemu:///system list --all \