Fix meta/salt.yml to workaround broken formulas

Change-Id: If8ee6ccfd282d8f926eff268cd74871e0f400754
diff --git a/salt/map.jinja b/salt/map.jinja
index 5bc540c..3a36ada 100644
--- a/salt/map.jinja
+++ b/salt/map.jinja
@@ -179,7 +179,7 @@
   virt_pkgs:
   - libvirt-dev
   - pkg-config
-{% if grains.oscodename == 'trusty' %}
+{% if grains.get('oscodename') == 'trusty' %}
   - libguestfs-tools
 {% endif %}
 
diff --git a/salt/meta/salt.yml b/salt/meta/salt.yml
index 6bc9632..cb50afd 100644
--- a/salt/meta/salt.yml
+++ b/salt/meta/salt.yml
@@ -4,7 +4,7 @@
   {%- macro load_grains_file() %}{% include grains_fragment_file ignore missing %}{% endmacro %}
   {%- set grains_yaml = load_grains_file()|load_yaml %}
   {%- if grains_yaml is mapping %}
-    {%- for node in grains_yaml.graph %}
+    {%- for node in grains_yaml.graph if grains_yaml.graph %}
     {%- do service_grains.salt.graph.append(node) %}
     {%- endfor %}
   {%- endif %}