Remove large backup from s3

[pgrzeszczak-neducatio]

Hi, I have problem with removing large backup from s3 storage.

When I try to remove backup with about 4k blocks, s3 returns error Handler for DELETE /backups returned error: AWS Error: MalformedXML The XML you provided was not well-formed or did not validate against our published schema <nil> 400

After that, backup is not available, but all unused block are not removed.