[console] stderr output from exec duplicated into a separate fd (?)

[Saviq]

Somehow stderr output gets duplicated into a separate FD, preventing its redirection into a file.

$ mp ls
Name                    State             IPv4             Image
awesome-gemsbok         Running           10.213.185.198   Ubuntu 18.04 LTS
$ ssh [email protected] bash -c 'echo stderr >&2; echo stdout' 2>/dev/null
stdout

# compared to

$ multipass exec awesome-gemsbok -- bash -c 'echo stderr >&2; echo stdout' 2>/dev/null
stderr
stdout
$ multipass exec awesome-gemsbok -- bash -c 'echo stderr >&2; echo stdout' >/dev/null 
stderr