Correction for issue1265 (pdb bug with "with" statement). When an unfinished generator-iterator is garbage collected, PyEval_EvalFrameEx is called with a GeneratorExit exception set. This leads to funny results if the sys.settrace function itself makes use of generators. A visible effect is that the settrace function is reset to None. Another is that the eventual "finally" block of the generator is not called. It is necessary to save/restore the exception around the call to the trace function. This happens a lot with py3k: isinstance() of an ABCMeta instance runs def __instancecheck__(cls, instance): """Override for isinstance(instance, cls).""" return any(cls.__subclasscheck__(c) for c in {instance.__class__, type(instance)}) which lets an opened generator expression each time it returns True. Seems a backport candidate, even if the case is less frequent in 2.5.

#include "pyconfig.h"
#include "pyfpe.h"
/* 
 * The signal handler for SIGFPE is actually declared in an external
 * module fpectl, or as preferred by the user.  These variable
 * definitions are required in order to compile Python without
 * getting missing externals, but to actually handle SIGFPE requires
 * defining a handler and enabling generation of SIGFPE.
 */

#ifdef WANT_SIGFPE_HANDLER
jmp_buf PyFPE_jbuf;
int PyFPE_counter = 0;
#endif

/* Have this outside the above #ifdef, since some picky ANSI compilers issue a 
   warning when compiling an empty file. */

double
PyFPE_dummy(void *dummy)
{
	return 1.0;
}