How do I simulate the ftp without it making physical changes?

This may be a stupid question as I'm still learning much about bzr, but can I simulate the bzr upload process without it changing files on the remote site? i.e. To tell me what it's going to add/modify/delete on the remote site without actually making the changes.

Reason being that I'm using "bzr upload ..\tmp" to copy the files locally so I can more quickly upload the entire tree but I want to make doubly sure that when I do upload to a live ftp site, that it's not going to overwrite anything I don't expect it to (like config files or anything I may have forgotten to "ignore".

Thanks in advance!