Magic sauce

gistfile1.m

NSString *pathToRelaunch = [host bundlePath];
if ([[updater delegate] respondsToSelector:@selector(pathToRelaunchForUpdater:)])
    pathToRelaunch = [[updater delegate] pathToRelaunchForUpdater:updater];

NSString *relaunchToolPath = [relaunchPath stringByAppendingPathComponent: @"/Contents/MacOS/finish_installation"];
[NSTask launchedTaskWithLaunchPath: relaunchToolPath arguments:[NSArray arrayWithObjects:[host bundlePath], pathToRelaunch, [NSString stringWithFormat:@"%d", [[NSProcessInfo processInfo] processIdentifier]], tempDir, relaunch ? @"1" : @"0", nil]];

[NSApp terminate:self];