`-nofork` doesn't seem to work at all. When persist mode is not set,

[yoe]

Also, -nofork doesn't seem to work at all. When persist mode is not set, nbd-client -nofork nbd0 immediately exits when it should not exit

# nbd-client -nofork nbd0
Negotiation: ..size = 1907695MB
Error: Failed to setup device, check dmesg

Exiting.

Originally posted by @candrews in #200 (comment)