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

Change-Id: Iafdf4455bdf1e91a734fd35df188564a5df949c9
Related: PROD-29251
diff --git a/.kitchen.yml b/.kitchen.yml
index b73890c..4e883fc 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: apache
       repo: git
       source: https://gerrit.mcp.mirantis.com/salt-formulas/apache
+      branch: <%=ENV['GERRIT_BRANCH'] || 'master' %>
   state_top:
     base:
       "*":