Correct SUDO detection on Mac OS X

[anthonygelibert]

Correct SUDO detection on Mac OS X where true isn't a provided as a /bin command.

[dolmen]

So where is the true binary stored?

$ which true

[anthonygelibert]

Excuse-me… I was pretty hurry, I thought it was only a "shell built-in command" ("which true" in my ZSH).

After your answer, I checked with bash and it's in /usr/bin/true.

So, maybe a:
sudo env true

Will be better?

[dolmen]

The point of this line is to run quickly a dummy command that has a 0 exit code.
env true would fork one more time, so this misses the point.
I'm merging your patch as is.

[dolmen]

Cherry-picked as 3d3061c. Thanks!