galera.galera_sst_mariabackup_encrypt_with_key failed for RHEL6 and Debian8:

galera.galera_sst_mariabackup_encrypt_with_key 'innodb' w1 [ fail ]
Test ended at 2019-12-18 22:39:13

CURRENT_TEST: galera.galera_sst_mariabackup_encrypt_with_key

Failed to start mysqld.2
mysqltest failed but provided no output

• saving '/var/tmp/mtr/1/log/galera.galera_sst_mariabackup_encrypt_with_key-innodb/' to '/var/tmp/mtr/log/galera.galera_sst_mariabackup_encrypt_with_key-innodb/'
  ***Warnings generated in error logs during shutdown after running tests: galera.galera_sst_mariabackup_encrypt_with_key

WSREP_SST: [ERROR] Error while getting data from donor node: exit codes: 0 1 (20191218 22:39:12.546)
WSREP_SST: [ERROR] Cleanup after exit with status:32 (20191218 22:39:12.550)
2019-12-18 22:39:12 139668351862528 [ERROR] WSREP: Failed to read from: wsrep_sst_mariabackup --role 'donor' --address '127.0.0.1:16027/xtrabackup_sst//1' --socket '/var/tmp/mtr/tmp/1/mysqld.1.sock' --datadir '/var/tmp/mtr/1/mysqld.1/data/' --defaults-file '/var/tmp/mtr/1/my.cnf' --defaults-group-suffix '.1' --gtid '1e055dac-2211-11ea-8941-a6ab2b211b50:0' --gtid-domain-id '0' --mysqld-args --defaults-group-suffix=.1 --defaults-file=/var/tmp/mtr/1/my.cnf --log-output=file --innodb --innodb-cmpmem --innodb-cmp-per-index --innodb-trx --innodb-locks --innodb-metrics --innodb-buffer-pool-stats --innodb-buffer-page --innodb-buffer-page-lru --innodb-sys-columns --innodb-sys-fields --innodb-sys-foreign --innodb-sys-foreign-cols --innodb-sys-indexes --innodb-sys-tables --innodb-sys-virtual --core-file --loose-debug-sync-timeout=300
2019-12-18 22:39:12 139668351862528 [ERROR] WSREP: Process completed with error: wsrep_sst_mariabackup --role 'donor' --address '127.0.0.1:16027/xtrabackup_sst//1' --socket '/var/tmp/mtr/tmp/1/mysqld.1.sock' --datadir '/var/tmp/mtr/1/mysqld.1/data/' --defaults-file '/var/tmp/mtr/1/my.cnf' --defaults-group-suffix '.1' --gtid '1e055dac-2211-11ea-8941-a6ab2b211b50:0' --gtid-domain-id '0' --mysqld-args --defaults-group-suffix=.1 --defaults-file=/var/tmp/mtr/1/my.cnf --log-output=file --innodb --innodb-cmpmem --innodb-cmp-per-index --innodb-trx --innodb-locks --innodb-metrics --innodb-buffer-pool-stats --innodb-buffer-page --innodb-buffer-page-lru --innodb-sys-columns --innodb-sys-fields --innodb-sys-foreign --innodb-sys-foreign-cols --innodb-sys-indexes --innodb-sys-tables --innodb-sys-virtual --core-file --loose-debug-sync-timeout=300: 32 (Broken pipe)
2019-12-18 22:39:12 139668351862528 [ERROR] WSREP: Command did not run: wsrep_sst_mariabackup --role 'donor' --address '127.0.0.1:16027/xtrabackup_sst//1' --socket '/var/tmp/mtr/tmp/1/mysqld.1.sock' --datadir '/var/tmp/mtr/1/mysqld.1/data/' --defaults-file '/var/tmp/mtr/1/my.cnf' --defaults-group-suffix '.1' --gtid '1e055dac-2211-11ea-8941-a6ab2b211b50:0' --gtid-domain-id '0' --mysqld-args --defaults-group-suffix=.1 --defaults-file=/var/tmp/mtr/1/my.cnf --log-output=file --innodb --innodb-cmpmem --innodb-cmp-per-index --innodb-trx --innodb-locks --innodb-metrics --innodb-buffer-pool-stats --innodb-buffer-page --innodb-buffer-page-lru --innodb-sys-columns --innodb-sys-fields --innodb-sys-foreign --innodb-sys-foreign-cols --innodb-sys-indexes --innodb-sys-tables --innodb-sys-virtual --core-file --loose-debug-sync-timeout=300
2019-12-18 22:39:12 139669115238144 [Warning] WSREP: 0.0 (ff2e7b97deda): State transfer to 1.0 (ff2e7b97deda) failed: -32 (Broken pipe)
WSREP_SST: [ERROR] Error while getting data from donor node: exit codes: 1 0 (20191218 22:39:12.545)
WSREP_SST: [ERROR] Cleanup after exit with status:32 (20191218 22:39:12.547)
2019-12-18 22:39:12 140242906138368 [ERROR] WSREP: Process completed with error: wsrep_sst_mariabackup --role 'joiner' --address '127.0.0.1:16027' --datadir '/var/tmp/mtr/1/mysqld.2/data/' --defaults-file '/var/tmp/mtr/1/my.cnf' --defaults-group-suffix '.2' --parent '79912' --binlog-index 'mysqld-bin.index' --mysqld-args --defaults-group-suffix=.2 --defaults-file=/var/tmp/mtr/1/my.cnf --log-output=file --innodb --innodb-cmpmem --innodb-cmp-per-index --innodb-trx --innodb-locks --innodb-metrics --innodb-buffer-pool-stats --innodb-buffer-page --innodb-buffer-page-lru --innodb-sys-columns --innodb-sys-fields --innodb-sys-foreign --innodb-sys-foreign-cols --innodb-sys-indexes --innodb-sys-tables --innodb-sys-virtual --core-file --loose-debug-sync-timeout=300: 32 (Broken pipe)
2019-12-18 22:39:12 140242906138368 [ERROR] WSREP: Failed to read uuid:seqno and wsrep_gtid_domain_id from joiner script.
2019-12-18 22:39:12 140243112196064 [ERROR] WSREP: SST failed: 32 (Broken pipe)
2019-12-18 22:39:12 140243112196064 [ERROR] Aborting
2019-12-18 22:39:12 140242915137280 [Warning] WSREP: 0.0 (ff2e7b97deda): State transfer to 1.0 (ff2e7b97deda) failed: -32 (Broken pipe)
2019-12-18 22:39:12 140242915137280 [ERROR] WSREP: gcs/src/gcs_group.cpp:gcs_group_handle_join_msg():775: Will never receive state. Need to abort.