The SSH_PID variable doesn't get expanded in the trap because of the
single quotes. Change to double quotes.
This is an example how the change works:
$ FOO="bar"
$ echo '$FOO'
$FOO
$ echo "$FOO"
bar
Lots of places used sort (or sort -u) but didn't set LC_ALL=C. This
means it could be slightly different on different people's systems. Make
it deterministic.
