When running unit tests, it's possible for Bazaar SSH unit tests to error out, and the reason isn't immediately obvious.

One major cause of this is the lack of a bzr command line utility installed globally. When communicating over SSH, bzr will invoke bzr remotely, and if this isn't installed globally, this will fail.

The exact error that's received is:

bash: bzr: command not found
ConnectionReset reading response for 'BzrDir.open_2.1', retrying
bash: bzr: command not found
bzr: ERROR: Connection closed: Unexpected end of message. Please check connectivity and permissions, and report a bug if problems persist.

A future fix would be to inspect the error looking for a "command not found" and to present a better error message.