NixOS/nix — pull request #66 by aszlig (2012-11-15 12:27:24+00:00)
Title: Ignore status of killUser() process on darwin.

Quoting from the man page of *kill(2)*:

```
If pid is -1:
If the user has super-user privileges, the signal is
sent to all processes excluding system processes and the
process sending the signal. If the user is not the super
user, the signal is sent to all processes with the same
uid as the user, excluding the process sending the
signal. No error is returned if any process could be
signaled.
```

Unfortunately this is not the case and the process sending the signal is killed as well, so we can't assume that wait() will return 0 if the process drops dead in-between.