Deep merge of pillar lists

salt/utils/dictupdate.py

@@ -42,6 +42,9 @@ def update(dest, upd, recursive_update=True):
                     and isinstance(val, collections.Mapping):
                 ret = update(dest_subkey, val)
                 dest[key] = ret
+            elif isinstance(dest_subkey, list) \
+                     and isinstance(val, list):
+                dest[key] = dest.get(key, []) + val
             else:
                 dest[key] = upd[key]
         return dest