Splitting this out from issue2720:

For issue2333, we get:

> darcs: security: createProcess: posix_spawnp: does not exist (No such file or directory)

The problem seems to be that darcs, or probably some library it
calls or the OS, is trying to invoke a binary called 'security',
which lives in /usr/bin.

This goes wrong in this line:

> PATH='' $thedarcs push ../S -a

Changing the line to `PATH='/usr/bin' ...` fixes the test.

I need to do some more digging to understand how this is supposed
to fit together and what the best thing for the test is.

Sorry, meant to make an issue not a patch!