Updating Build File During Build

[SuperJason]

Is there a good way to make a build file self updating from source control?

I want to have some steps in a build that retrieve the newest BLD file from source control, and if it has changed, restart the new version of the build. I don't know how to do this because I don't know if the build file got changed. I also don't know if the build was launched with the GUI or the command line version. I want to reopen the file the same way.

I'd like to hear any advice you may have.

Thanks,
Jason