It hangs "forever" which is to say I gave up on it after 5-10 mins.
I discovered the issue.
I saw a similar issue discussed on a github ticket but initially didn't pay much attention to since it seemed relevant to the server and not the TransportClient.
The issue was I have a mount point whose filesystem (NFS) was not mounted. It appears the client attempts to enumerate mount points. Because the filesystem wasn't mounted the client was hanging indefinitely.
A line or two of documentation could mention this.