`aws s3 sync` is slow

[Atry]

We use aws s3 sync to upload deb packages from EBS to S3

packaging/bin/update-debianish-repo

Lines 49 to 50 in 6d30196

	aws s3 sync "$REPO_DIR/" "s3://hhvm-downloads/${DISTRO_BASE}/" --exclude '*' --include '*.deb' --include '*.orig.tar.gz'
	aws s3 sync "$REPO_DIR/" "s3://hhvm-downloads/${DISTRO_BASE}/"

According to the document, aws s3 sync will compare the content of all the 2TB files even when we just added 5GB files. It would be good to avoid checking the 2TB files.

[Atry]

Even though it is still not ideal, I think Fred had partially optimized it, because previously we had to downloading the 2TB files before the updating, which is worse.

[Atry]

Why not mount S3 with s3fs and directly run reprepro in the mounted path, instead of aws s3 sync?