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

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

Block pull request

# gpg: Signature made Fri 18 Jul 2014 13:39:43 BST using RSA key ID 81AB73C8
# gpg: Good signature from "Stefan Hajnoczi <[email protected]>"
# gpg:                 aka "Stefan Hajnoczi <[email protected]>"

* remotes/stefanha/tags/block-pull-request:
  qemu-iotests: fix 028 failure due to disk image path
  raw-posix: Fail gracefully if no working alignment is found
  block: Add Error argument to bdrv_refresh_limits()
  qcow2: Fix error path for unknown incompatible features

Signed-off-by: Peter Maydell <[email protected]>