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

Change-Id: I51ec4b6e84f2a4422cc493a655c8da725fb01515
Related: PROD-29251
diff --git a/.kitchen.yml b/.kitchen.yml
index 97bffb8..5d6dd3f 100644
--- a/.kitchen.yml
+++ b/.kitchen.yml
@@ -18,12 +18,15 @@
     - 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' %>
     - name: oslo_templates
       repo: git
       source: https://gerrit.mcp.mirantis.com/salt-formulas/oslo-templates
+      branch: <%=ENV['GERRIT_BRANCH'] || 'master' %>
   state_top:
     base:
       "*":