Tagging for 2.7 release

Change-Id: I13eadfab5be83d1dcaec4002cb4452bd3d78beca
diff --git a/.gitreview b/.gitreview
index 4e39788..b5f2db0 100644
--- a/.gitreview
+++ b/.gitreview
@@ -3,3 +3,4 @@
 port=29418
 project=voltha-system-tests.git
 defaultremote=origin
+defaultbranch=voltha-2.7