itertools.py zip_longest fix __reduce__ (account for empty / none iterators)

Author: cosminbasca

graalpython/lib-graalpython/itertools.py

@@ -779,7 +779,7 @@ def __new__(subtype, iter1, *args, fillvalue=None):
 
     @__graalpython__.builtin_method
     def __reduce__(self):
-        return type(self), tuple(self.iterators), self.fillvalue
+        return type(self), tuple([(it if it else tuple()) for it in self.iterators]), self.fillvalue
 
 
     @__graalpython__.builtin_method

graalpython/lib-graalpython/object.py

@@ -90,7 +90,8 @@ def reduce_newobj(obj):
     try:
         getstate = obj.__getstate__
     except AttributeError:
-        if getattr(type(obj), '__itemsize__', None):
+        itemsize = getattr(type(obj), '__itemsize__', 0)
+        if itemsize != 0:
             raise TypeError("cannot pickle '{}' object".format(type(obj).__name__))
 
         state = getattr(obj, "__dict__", None)