MDEV-10.1.31 does not join an existing cluster with SST xtrabackup-v2

Analysis:- The problem  is the change in the implementation of wait_for_listen
in wsrep_sst_xtrabackup-v2.sh. The new script uses lsof which will always
exit with an error code if it can't find all the items, and because the
script has the -e option set in the hashbang line (#!/bin/bash -ue), the
script will abort right after running lsof if lsof can't find even a single
item among all the items listed in its arguments. This will happen even if
socat is running and listening, because it can't find nc. The loop in
wait_for_listen will therefore always quit after one iteration without
writing the "ready" line to signal the parent.

Solution:- We will or the lsof with true.

Patch Credit :Daniel Black and David Wang

scripts/wsrep_sst_xtrabackup-v2.sh

@@ -644,7 +644,7 @@ wait_for_listen()
 
     for i in {1..300}
     do
-        LSOF_OUT=$(lsof -sTCP:LISTEN -i TCP:${PORT} -a -c nc -c socat -F c)
+        LSOF_OUT=$(lsof -sTCP:LISTEN -i TCP:${PORT} -a -c nc -c socat -F c 2> /dev/null || :)
         [ -n "${LSOF_OUT}" ] && break
         sleep 0.2
     done