QDict: Fix size update

Key replacement should not update the dictionary's size.

This commit also adds a test for the bug.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/qdict.c b/qdict.c
index ef73265..ba8eef0 100644
--- a/qdict.c
+++ b/qdict.c
@@ -122,9 +122,8 @@
         /* allocate a new entry */
         entry = alloc_entry(key, value);
         QLIST_INSERT_HEAD(&qdict->table[hash], entry, next);
+        qdict->size++;
     }
-
-    qdict->size++;
 }
 
 /**