backing up citus nodes with Barman

I'm trying to backup a Postgres Citus setup using Barman through a streaming-only configuration. I've set up server configs for the coordinator and backup nodes in Barman.

WAL streaming seems to work just fine. However, whenever I initiate a `barman backup pg`, the backup will never move past the backup started phase. In the barman.log file I've noticed an error which will get logged 3 or 4 times in a row when the backup has been running for a bit.
Once the base_backup inevitably fails, `barman show-backup` displays `error 143 failure copying files`

`barman check pg` indicates all OK.

Here is the error which will show up 3 or 4 times in a row after the backup has been started for a while.

```
2018-10-29 00:12:39,647 [2788] barman.cli ERROR: 'Namespace' object has no attribute 'server_name'
See log file for more details
Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/barman/cli.py", line 1162, in main
p.dispatch(pre_call=global_config)
File "/usr/lib/python2.7/dist-packages/argh/helpers.py", line 55, in dispatch
return dispatch(self, *args, **kwargs)
File "/usr/lib/python2.7/dist-packages/argh/dispatching.py", line 133, in dispatch
autocomplete(parser)
File "/usr/lib/python2.7/dist-packages/argh/completion.py", line 92, in autocomplete
argcomplete.autocomplete(parser)
File "/usr/lib/python2.7/dist-packages/argcomplete/__init__.py", line 213, in __call__
completions = self._get_completions(comp_words, cword_prefix, cword_prequote, first_colon_pos)
File "/usr/lib/python2.7/dist-packages/argcomplete/__init__.py", line 243, in _get_completions
completions = self.collect_completions(active_parsers, parsed_args, cword_prefix, debug)
File "/usr/lib/python2.7/dist-packages/argcomplete/__init__.py", line 430, in collect_completions
completions)
File "/usr/lib/python2.7/dist-packages/argcomplete/__init__.py", line 372, in _complete_active_option
prefix=cword_prefix, action=active_action, parsed_args=parsed_args)
File "/usr/lib/python2.7/dist-packages/barman/cli.py", line 166, in backup_completer
server = get_server(parsed_args)
File "/usr/lib/python2.7/dist-packages/barman/cli.py", line 924, in get_server
name = args.server_name
AttributeError: 'Namespace' object has no attribute 'server_name'

```
I've tried asking on the barman support sites but I haven't gotten any response. Is Barman known to not work with Citus nodes? If so, what are some other backup tools that I should look into?