[PVE-User] Adding info to backup email from hook script "job-start" phase

[Dietmar Maurer]

> > Anything you write to stdout/stderr should show up in the backup log.
> 
> 
> Only the stuff printed after each individual "backup-start" seems to show up, in
> the vm backup log. Output in "job-start", before the vm backups themselves is
> not there.

So why are there things like 'backup mode:' which are printed before we run
the 'backup-start' hook?

I just saw that we pass the logfd to the hook script like:

	    $self->run_hook_script ('backup-start', $task, $logfd);

So please try to print to $logfd instead of stdout/stderr.