For your consideration:
Trac Ticket #510: Modified 'cobbler buildiso' to use /var/cache/cobbler/buildiso by default. Added a /etc/cobbler/settings value of 'buildisodir' to make it setable by the end user. --tempdir will still overwrite either setting on the command line. (https://fedorahosted.org/cobbler/ticket/510)
Trac Ticket #509: Added 'self' as a argument to self.on_done() to keep the web interface from stating that buildiso failed. (https://fedorahosted.org/cobbler/ticket/509)
Andrew