Can't make second command die when parent shell dies

unexpected.md

When I execute the following:

su - deployer -c "ls; sleep 250"

It outputs the ls and then sleeps for a few minutes. If I hit Ctrl+C, I get this output:

Session terminated, terminating shell... ...killed.

But then, this happens and I do not expect it:

root@machine:# ps ax|grep slee
29918 ?        S      0:00 sleep 250

That is, the sleep process is still running, even though its parent process was terminated.

How can I structure this such that the parent process' death also results in this sleep process' death?

This is causing me grief because I have a similar setup, but cannot get my daemontools or upstart scripts to reliably bring the process down.