Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

More block layer patches for 2.7.0-rc2

# gpg: Signature made Mon 08 Aug 2016 12:51:30 BST
# gpg:                using RSA key 0x7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <[email protected]>"
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
  iotests: fix 109
  mirror: finish earlier on error
  tests: Test blockjob IDs
  block/qdev: Let 'drive' property fall back to node name

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