[Patches] Change to attribute error message for instances.

[Mark Hammond]

In line with a similar checkin to object.c a while ago, this patch
gives a more descriptive error message for an attribute error on a
class instance.  The message now looks like:

AttributeError: 'Descriptor' instance has no attribute
'GetReturnType'

[Maybe the module name would also be useful, but IMO this is fine
and a nice improvement]

Release info:

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Mark.

diff -c -2 -r2.83 classobject.c
*** classobject.c	2000/02/28 15:03:15	2.83
--- classobject.c	2000/04/10 03:01:08
***************
*** 593,597 ****
  		v = class_lookup(inst->in_class, name, &class);
  		if (v == NULL) {
! 			PyErr_SetObject(PyExc_AttributeError, name);
  			return NULL;
  		}
--- 593,600 ----
  		v = class_lookup(inst->in_class, name, &class);
  		if (v == NULL) {
! 			PyErr_Format(PyExc_AttributeError,
! 				     "'%.50s' instance has no attribute '%.400s'",
! 				     PyString_AsString(inst->in_class->cl_name),
! 				     sname);
  			return NULL;
  		}