* set sq_repeat and sq_concat to NULL for user-defined new-style
classes, as a way to fix a number of related problems. See
test_descr.notimplemented()). One of these problems was fixed
in r25556 and r25557 but many more existed; this is a general
fix and thus reverts r25556-r25557.
* to avoid having PySequence_Repeat()/PySequence_Concat() failing
on user-defined classes, they now fall back to nb_add/nb_mul if
sq_concat/sq_repeat are not defined and the arguments appear to
be sequences.
* added tests.
Backport candidate.
Fix over-aggressive PyErr_Clear(). The same code fragment appears in
various guises in list.extend(), map(), filter(), zip(), and internally
in PySequence_Tuple().
[ 1229429 ] missing Py_DECREF in PyObject_CallMethod
Add a test in test_enumerate, which is a bit random, but suffices
(reversed_new calls PyObject_CallMethod under some circumstances).
conversion using the proper magic slot (e.g., __int__()). Also move conversion
code out of PyNumber_*() functions in the C API into the nb_* function.
Applied patch #1109424. Thanks Walter Doewald.
* Added missing error checks.
* Fixed O(n**2) growth pattern. Modeled after lists to achieve linear
amortized resizing. Improves construction of "tuple(it)" when "it" is
large and does not have a __len__ method. Other cases are unaffected.
Make PySequence_Check() and PyMapping_Check() handle NULL inputs. This
goes beyond what most of the other checks do, but it is nice defensive
programming and solves the OP's problem.
__oct__, and __hex__. Raise TypeError if an invalid type is
returned. Note that PyNumber_Int and PyNumber_Long can still
return ints or longs. Fixes SF bug #966618.
