Correct exception thrown attempting to access a non-existent C/C++ global variable on the 'cvar' object.

The exception thrown used to be a NameError. However, as this access is
via a primary, an AttributeError is more correct and so the exception
thrown now is an AttributeError. Reference:
http://docs.python.org/2/reference/expressions.html#attribute-references

SF Patch #346.

CHANGES.current

@@ -5,6 +5,15 @@ See the RELEASENOTES file for a summary of changes in each release.
 Version 3.0.0 (in progress)
 ============================
 
+2014-03-02: wsfulton
+	    [Python] SF Patch #346 from Jens Krueger. Correct exception thrown attempting to
+            access a non-existent C/C++ global variable on the 'cvar' object. The exception thrown
+            used to be a NameError. However, as this access is via a primary, an AttributeError
+            is more correct and so the exception thrown now is an AttributeError. Reference:
+            http://docs.python.org/2/reference/expressions.html#attribute-references
+
+            *** POTENTIAL INCOMPATIBILITY  ***
+
 2014-03-01: wsfulton
 	    [Python] Patch #143 Fix type shown when using type() to include the module and package
             name when using -builtin.

Examples/test-suite/global_vars.i

@@ -28,4 +28,9 @@
   Hello h;
   Hello *hp;
   Hello &hr = h;
+
+  void init() {
+    b = "string b";
+    x = 1234;
+  }
 %}

Lib/python/pyinit.swg

@@ -116,7 +116,7 @@ swig_varlink_getattr(swig_varlinkobject *v, char *n) {
     var = var->next;
   }
   if (res == NULL && !PyErr_Occurred()) {
-    PyErr_SetString(PyExc_AttributeError,"Unknown C global variable");
+    PyErr_Format(PyExc_AttributeError, "Unknown C global variable '%s'", n);
   }
   return res;
 }
@@ -133,7 +133,7 @@ swig_varlink_setattr(swig_varlinkobject *v, char *n, PyObject *p) {
     var = var->next;
   }
   if (res == 1 && !PyErr_Occurred()) {
-    PyErr_SetString(PyExc_NameError,"Unknown C global variable");
+    PyErr_Format(PyExc_AttributeError, "Unknown C global variable '%s'", n);
   }
   return res;
 }