sprite.command.output intermittently fails with ExecError: 1 even for trivial commands

[Roadmaster]

When using the sprites-py SDK, commands intermittently fail with
ExecError: 1 even when the command itself is trivial and should never
fail:

>>> self.sprite.command("echo", "test").output()

b'test\n'

>>> self.sprite.command("echo", "test").output()

*** sprites.exceptions.ExecError: 1

>>> self.sprite.command("echo", "test").output()

b'test\n'

>>> self.sprite.command("echo", "test").output()

b'test\n'

>>> self.sprite.command("echo", "test").output()

*** sprites.exceptions.ExecError: 1

This happens both in interactive debugging (ipdb) and normal program
execution

Tracing the Code Path

1. sprite.command("echo", "test") creates a Cmd object (sprite.py)

2. .output() calls _run_sync() which calls _run_async() (exec.py)

3. _run_async() delegates to run_ws_command() (websocket.py)