Per buildfarm member conchuela and Kyotaro Horiguchi, it's possible
 for the WAL segment that the cascading standby needs to be removed
 too quickly. Hopefully this will prevent that. 
 Kyotaro Horiguchi 
 Discussion: http://postgr.es/m/
20210610.101240.
1270925505780628275.horikyota.ntt@gmail.com  
 
           my $archivedir_primary = $node_primary->archive_dir;
  $node_primary->append_conf('postgresql.conf', qq(
  archive_command = '$perlbin "$FindBin::RealBin/cp_history_files" "%p" "$archivedir_primary/%f"'
 +wal_keep_size=128MB
  ));
  $node_primary->start;