I'm a little leery of this approach for updating the XML files.  The parse-modify-reprint cycle seems fairly lossy...  The installer XML files are still mostly hand-coded, and losing all the formatting is kind of a drag.  It's also a little scary that it strips the DOCTYPE from the plist XML file... Apple can be very picky; is that something part of OS X might care about?

Would you feel comfortable using the less-churny regexp approach for XML files too?  Might be a tad trickier than the other simple regexps, but hopefully not by _too_ much.  I'd actually suggest for _all_ the regexp-based replacements, having some sort of safety check so that we error out if the format changes in such a way to make the replacement no-op.  Something like this:

```javascript
function safeReplace(content, regexp, replacement) {
    var newContent = content.replace(regexp, replacement);
    if (newContent === content)
        fail_the_build();
}
```

That coupled with the fact that the diffs in the pull request will still get reviewed should make it reasonably safe...