=== DF-2622 run A: volume='@' ===
mnt2622: mount(volume="@", mp=/mnt/h2x) FAILED errno=2 (No such file or directory)
=== DF-2622 run B: volume='' (empty) ===
mnt2622: mount(volume="", mp=/mnt/h2x) FAILED errno=2 (No such file or directory)
=== DF-2622 run C (control): volume='/dev/vn0@nosuchlabel' ===
mnt2622: mount(volume="/dev/vn0@nosuchlabel", mp=/mnt/h2x) FAILED errno=2 (No such file or directory)
=== DF-2622 run D (control): volume='/dev/vn0s1d@' (trailing @, real slice) ===
mnt2622: mount(volume="/dev/vn0@", mp=/mnt/h2x) FAILED errno=2 (No such file or directory)
DF2622_DONE