S3 sync should be applied filters to destination when "--delete" is specified

[jamesls]

If I have:

local           remote
-----           ------

a.txt           a.txt
                b.py

And I run aws s3 sync local remote --exclude '*.py' --delete, we are currently deleting "b.py". This is because we only apply filters to the sending side, which outside of the "--delete" flag, is all that's required. When "--delete" is specified, we need to run all the filters against the sending and receiving side so that we don't inadvertently delete files.

Our current behavior is similar to rsync's --exclude '*.py' --delete-excluded and we should instead be like rsync's --exclude '*.py' --delete.

This is technically a change in behavior, but we will now no longer be deleting files we were previously deleting so it is a non-destructive change. I think this bug is important enough to change the behavior of --exclude rather than adding a new argument. If anyone wants the previous behavior we can add rsync's --delete-excluded argument.

[jamesls]

So I have an initial fix for this linked above, but after investigating further, I'm wondering whether or not it makes sense to just adopt rsync's semantics for exclude/include filters. Most users are familiar with rsync so it would be easier to explain if we had the same behavior.

I'd need to do an analysis and see what all the changes would be, and exactly what the delta would be from the existing behavior.

[jamesls]

I spent some time looking into adopting the rsync exclude/include filters and it would be too big of a change in behavior to change exclude/include semantics. We could possible add either mutually exclusive args that have the rsync style exclude/includes but I'm not sure the complexity is worth it at this point. For now, #780 fixes the immediate issue so I'm going to close this issue.