Installation fails after trying to open a non-existant file in /tmp

[callumlocke]

This is from running curl get.pow.cx | sh on my new Macbook Pro with Mountain Lion:

  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  6887  100  6887    0     0  14876      0 --:--:-- --:--:-- --:--:-- 23266
*** Installing Pow 0.4.0...
*** Installing local configuration files...
*** Installing system configuration files as root...
Password:

/Users/callum.locke/Library/Application Support/Pow/Versions/0.4.0/lib/command.js:19
      throw err;
            ^
Error: ENOENT, open '/tmp/pow.87588.1352661160427.21167'

I've checked in /tmp and there's no such file there, hence the ENOENT. The installation doesn't seem to cause any new files to appear in /tmp at any stage.

Any ideas?

[callumlocke]

Sorry, this is a dupe of #297; I've just added my report as a comment there.