[sheepdog] [ANNOUNCE, CAUTION] sheepdog stable release v0.8.3

[Hitoshi Mitake]

Hi sheepdog users and developers,

I released v0.8.3 of stable branch. You can download a source archive
from these URLs:
tar.gz: https://github.com/sheepdog/sheepdog/archive/v0.8.3.tar.gz
zip: https://github.com/sheepdog/sheepdog/archive/v0.8.3.zip

I have to emphasis on the point that updating from v0.8.x (x < 3) to
v0.8.3 requires "-u" option, because it contains updating store
format. Sorry for inconvenience but the format update is a necessary
change for clusters which store many objects.

Below is a summary of commits backported after v0.8.2:

Bingpeng Zhu (1):
      sheep/cluster: fix error in sheep log

Liu Yuan (2):
      tests/func: fix spurious error for 032
      cluster/zookeeper: add log information for zk auto-recoonect

Meng An (1):
      sheep: remove last slash for new->path in md_add_disk()

Robin Dong (2):
      sheep/md: add main_fn marker to for_each_object_in_wd()
      sheep/md: called get_vnode_info() only once in for_each_object_in_wd()

Ruoyu (10):
      sheep/zookeeper: ensure zookeeper is connected
      zk_control: add list and purge queue nodes
      zookeeper: fix zk_event structure not initialized
      sheep/ops: fix incorrect error log on remove_epoch
      sheep/request: straightforward error message in sheep_exec_req
      lib/event: fix and unify error message
      sheep/cluster: remove ephemeral node when zookeeper master leaves
      sheep/request: fix fd leak
      tests/unit: unit test failed because interfaces were changed.
      sheep: fix sheep sometimes cannot be killed successfully


Thanks,
Hitoshi