From b8d057296a4096047f0d6fe07e032e13f6879996 Mon Sep 17 00:00:00 2001
From: Serge van Ginderachter <serge@vanginderachter.be>
Date: Thu, 21 Aug 2014 17:40:47 +0200
Subject: [PATCH] variable merging: detect if both vars are really dicts when
 combining/merging dicts

---
 lib/ansible/utils/__init__.py | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/ansible/utils/__init__.py b/lib/ansible/utils/__init__.py
index c18174b00d2..401d35ed860 100644
--- a/lib/ansible/utils/__init__.py
+++ b/lib/ansible/utils/__init__.py
@@ -696,10 +696,17 @@ def parse_kv(args):
                 options[k.strip()] = unquote(v.strip())
     return options
 
+def _validate_both_dicts(a, b):
+
+    if not (isinstance(a, dict) and isinstance(b, dict)):
+        raise errors.AnsibleError("Failed to combine two values which are not "
+            "both hashes, got these differing values now:\n\n%s\n and\n%s" % (a, b))
+
 def merge_hash(a, b):
     ''' recursively merges hash b into a
     keys from b take precedence over keys from a '''
 
+    _validate_both_dicts(a, b)
     result = {}
 
     for dicts in a, b:
@@ -1308,6 +1315,8 @@ def listify_lookup_plugin_terms(terms, basedir, inject):
 
 def combine_vars(a, b):
 
+    _validate_both_dicts(a, b)
+
     if C.DEFAULT_HASH_BEHAVIOUR == "merge":
         return merge_hash(a, b)
     else: