This is using a specif revision instead of release because
we need commit 23731b to fix FAB-13920: long leader failover
when `CheckQuorum` and `PreVote` are enabled, due to lease
check in raft. At the time of upgrading, that commit is not
included in any of etcd release yet.

Change-Id: I0467352d35180f45a9931d7afd66f82d6c10990d
Signed-off-by: Jay Guo <guojiannan1101@gmail.com>