Merge branch 'stable-3.9'

* stable-3.9:
  Fix ApplyObjectActionIT flakiness due to the wrong ref used
  Force async fetch as a fallback for sync replication
  Index change asynchronously upon refs replicated event
  Address follow-up comments to Change 396868
  Introduce wait for replication events to reduce flaky tests
  Fail apply-object on change /meta when missing patch-set

Change-Id: Ib0783cb2b0863f7327b415ee9917956e1cc5f1a1