[pygobject] Use PyMapping_Keys to determine if an object is a dict (py3k fix)

[Tomeu Vizoso <tomeuv src gnome org>]

commit b855562e5c0019cd7e4982fe00c467ede9e3926d
Author: John (J5) Palmieri <johnp redhat com>
Date:   Thu Sep 9 22:16:58 2010 -0400

    Use PyMapping_Keys to determine if an object is a dict (py3k fix)
    
    * in Py3k PyMapping_Check returns true for sequences such as strings
      and lists.  Since we need to get the keys anyway, and it returns
      NULL if this is not a dict, this is a much better test, even in
      Py2
    
    https://bugzilla.gnome.org/show_bug.cgi?id=615872

 gi/pygi-argument.c |   10 +++-------
 1 files changed, 3 insertions(+), 7 deletions(-)
---
diff --git a/gi/pygi-argument.c b/gi/pygi-argument.c
index 1f8b652..301a767 100644
--- a/gi/pygi-argument.c
+++ b/gi/pygi-argument.c
@@ -497,7 +497,8 @@ check_number_release:
             GITypeInfo *value_type_info;
             Py_ssize_t i;
 
-            if (!PyMapping_Check (object)) {
+            keys = PyMapping_Keys (object);
+            if (keys == NULL) {
                 PyErr_Format (PyExc_TypeError, "Must be mapping, not %s",
                               object->ob_type->tp_name);
                 retval = 0;
@@ -506,12 +507,7 @@ check_number_release:
 
             length = PyMapping_Length (object);
             if (length < 0) {
-                retval = -1;
-                break;
-            }
-
-            keys = PyMapping_Keys (object);
-            if (keys == NULL) {
+                Py_DECREF (keys);
                 retval = -1;
                 break;
             }