Make sure kitchen test dependencies formulas are always fetched from correct branch

Related: PROD-29251

Change-Id: Ib404cb9fca1f44d93119a76b03fdd0a324621724
diff --git a/.kitchen.yml b/.kitchen.yml
index 16f20f7..2919a16 100644
--- a/.kitchen.yml
+++ b/.kitchen.yml
@@ -18,9 +18,11 @@
     - name: linux
       repo: git
       source: https://gerrit.mcp.mirantis.com/salt-formulas/linux
+      branch: <%=ENV['GERRIT_BRANCH'] || 'master' %>
     - name: oslo_templates
       repo: git
       source: https://gerrit.mcp.mirantis.com/salt-formulas/oslo-templates
+      branch: <%=ENV['GERRIT_BRANCH'] || 'master' %>
   state_top:
     base:
       "*":