Merge remote-tracking branch 'remotes/cody/tags/block-pull-request' into staging

# gpg: Signature made Tue 08 May 2018 16:18:22 BST
# gpg:                using RSA key BDBE7B27C0DE3057
# gpg: Good signature from "Jeffrey Cody <jcody@redhat.com>"
# gpg:                 aka "Jeffrey Cody <jeff@codyprime.org>"
# gpg:                 aka "Jeffrey Cody <codyprime@gmail.com>"
# Primary key fingerprint: 9957 4B4D 3474 90E7 9D98  D624 BDBE 7B27 C0DE 3057

* remotes/cody/tags/block-pull-request:
  sheepdog: Fix sd_co_create_opts() memory leaks
  iotests: Add test for cancelling a mirror job
  block/mirror: Make cancel always cancel pre-READY
  block/mirror: honor ratelimit again

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