Merge branch 'stable-3.1' into stable-3.2

* stable-3.1:
  Set Gerrit to 3.1.12
  Set Gerrit to 3.0.16
  Set Gerrit to 2.16.26
  Set Gerrit to 3.1.11
  Set Gerrit to 3.0.15
  Set Gerrit to 2.16.25
  Set Gerrit to 3.1.10
  Set Gerrit to 3.1.9
  Set Gerrit to 3.0.14
  Set Gerrit to 2.16.24
  Set Gerrit to 2.16.23
  Set Gerrit to 3.0.13

Change-Id: I0f9e4652cdf89a408aaaa40b1ab6927e8d3fd9be