IPS (Intrusion Protection System), not ISP. And yes, they'd drop the connection on such an error response if configured to do so. (Which is likely what you want to do anyway in this case. Amazon's engineers had the foresight not to respond early in the case of a successful upload thankfully.)
Ah! Complete reading fail on my end. (thanks for the edit, it is much clearer now, I apparently substituted ISP for IPS).
I don't think it is possible to respond early in case of a successful upload, after all, that means the upload can still fail for a variety of reasons. Success indicates that you can move to the next state, and an 'early success' might still turn into a late failure.
