Backport 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. And the problem can be reproduced in 2.5 with pure python code.

/* Support for dynamic loading of extension modules */

#include "dl.h"

#include "Python.h"
#include "importdl.h"


extern char *Py_GetProgramName(void);

const struct filedescr _PyImport_DynLoadFiletab[] = {
	{".o", "rb", C_EXTENSION},
	{"module.o", "rb", C_EXTENSION},
	{0, 0}
};


dl_funcptr _PyImport_GetDynLoadFunc(const char *fqname, const char *shortname,
				    const char *pathname, FILE *fp)
{
	char funcname[258];

	PyOS_snprintf(funcname, sizeof(funcname), "init%.200s", shortname);
	return dl_loadmod(Py_GetProgramName(), pathname, funcname);
}