As the previous reply hints at, it has nothing to do with the ssh and everything with the ||. You can verify that it behaves the same way on a shell command line:

:/tmp/t # false; echo $?
1
:/tmp/t # false || echo FAIL; echo $?
FAIL
0
[download]

So either just remove the || echo FAIL part, or make it something like || { echo FAIL; exit 1 }