Update branches for stable/rocky

Change-Id: Ia6de4b83f56c5ac0af19b0ca4f12aa4d47fd963a
diff --git a/stackrc b/stackrc
index 2088bf4..2c464bd 100644
--- a/stackrc
+++ b/stackrc
@@ -15,7 +15,7 @@
 
 # Set the target branch. This is used so that stable branching
 # does not need to update each repo below.
-TARGET_BRANCH=master
+TARGET_BRANCH=stable/rocky
 
 # Cycle trailing projects need to branch later than the others.
 TRAILING_TARGET_BRANCH=master