I didn't find a git repo for the extras/executable-war. Here's the patch against SVN.
Note that the patch contains:
- the fix
- the same troubleshooting code I introduced in the following git pull https://github.com/jenkinsci/jenkins/pull/27
- a migration to java 1.5 and a removal of the catch for 1.4 related issues. This allows to make both WebAppMain.getHomeDir and Main.getHomeDir a bit more similar.
You may or you may not want to add all this debug code (I think it might help troubleshoot other people's installs.)