Hasher: trust cached sum

I am using Hasher on a remote that doesn't support any kind of checksum. It works fine as a database to keep different sums and I know it isn't intended for what I am trying to use it, but it would be useful to have a way to simply check against the hasher instead of updating cached sums during transfers.

I will make an example:
A file is corrupted during the upload to the remote, cached sum is the right one made locally. I'm downloading the file from the remote again
expected behaviour -> after a given number of retries the transfer fails because the two hashes differ.
actual behaviour -> no retries, once the file is fully read the hash gets updated with the corrupted one.

I am aware of the workaround using the chunker and I know the hasher isn't meant for this, but it's the nearest to my purpose. Maybe this could be a new flag or a new key in section?