Add gnocchiclient constraints to global pins

In order to ensure that the correct version of
gnocchiclient is built on the repo server, the
global pin is set. This does away with the need
for a deployer to set the upper constraint
override themselves.

Closes-Bug: #1670632
Change-Id: Id7751934aaab36558115748819e2aadeb483a75e

global-requirement-pins.txt

@@ -5,6 +5,13 @@
 #
 # Use this file with caution!
 #
+
+# Due to https://bugs.launchpad.net/ceilometer/+bug/1660800, gnocchiclient
+# must be pinned to < 3.0.0. This constraint matches what is defined in
+# the optional dependencies specified here:
+# https://github.com/openstack/ceilometer/blob/stable/newton/setup.cfg#L36
+gnocchiclient>=2.2.0,<3.0.0
+
 ###
 ### These are pinned to ensure exactly the same behaviour forever!   ###
 ### These pins are updated through the sources-branch-updater script ###

releasenotes/notes/gnocchiclient-fix-793d71eb9d8eb738.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - The workaround of requiring the addition of gnocchiclient
+    to the ``repo_build_upper_constraints_overrides`` variable
+    is no longer required. The appropriate constraints have
+    been implemented as a global pin.