I see the same with 15.4.3 p1-10 and 15.5.1.6
The command looks fine - I was wondering if it didn't like closing without "exit", so I did:
ssh -v user@switch "exit"but that, too, gave me a "-1", i.e. "255"
Heck, even on an interactive ssh session, once you type "exit", the return code is -1/255
Do we need to open a case?