fast-forward always pretends to be successful

[MJochim]

I have had two different cases where fast-forwarding an upload prints a green success message when in fact nothing has happened at all:

• When the uploaded Git tree does not extend the current Git tree linearly
• When the uploaded Zip contains changes but no new commits (the uncommitted changes are ignored and technically, yes, the (null-)fast-forward worked but this is not what user would reasonably expect)