Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2020-08-11' into staging

Block patches for 5.1.0-rc4:
- Fix abort when running a backup job on an image whose size is not
  aligned to the backup job's cluster size

# gpg: Signature made Tue 11 Aug 2020 10:29:27 BST
# gpg:                using RSA key 91BEB60A30DB3E8857D11829F407DB0061D5CF40
# gpg:                issuer "mreitz@redhat.com"
# gpg: Good signature from "Max Reitz <mreitz@redhat.com>" [full]
# Primary key fingerprint: 91BE B60A 30DB 3E88 57D1  1829 F407 DB00 61D5 CF40

* remotes/maxreitz/tags/pull-block-2020-08-11:
  iotests: add test for unaligned granularity bitmap backup
  block/block-copy: always align copied region to cluster size

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>