deepcopy debugging

[Robin Becker]

I'm using deepcopy in some code which eventually ends up by crash witht he
following rather long winded error. I'm not directly using _hashlib.HASH, but I
suppose something else along the way could be. Is there some nice way to make
copy/deepcopy give more information when this error happens? I know what the top
level object is, but presumably it's something further down that's causing the
problem.

..........

File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 291, in _deepcopy_inst
state = deepcopy(state, memo)
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 254, in _deepcopy_dict
y[deepcopy(key, memo)] = deepcopy(value, memo)
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 234, in _deepcopy_tuple
y.append(deepcopy(a, memo))
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 227, in _deepcopy_list
y.append(deepcopy(a, memo))
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 291, in _deepcopy_inst
state = deepcopy(state, memo)
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 254, in _deepcopy_dict
y[deepcopy(key, memo)] = deepcopy(value, memo)
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 234, in _deepcopy_tuple
y.append(deepcopy(a, memo))
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 234, in _deepcopy_tuple
y.append(deepcopy(a, memo))
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 291, in _deepcopy_inst
state = deepcopy(state, memo)
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 254, in _deepcopy_dict
y[deepcopy(key, memo)] = deepcopy(value, memo)
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 291, in _deepcopy_inst
state = deepcopy(state, memo)
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 254, in _deepcopy_dict
y[deepcopy(key, memo)] = deepcopy(value, memo)
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 291, in _deepcopy_inst
state = deepcopy(state, memo)
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 254, in _deepcopy_dict
y[deepcopy(key, memo)] = deepcopy(value, memo)
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 291, in _deepcopy_inst
state = deepcopy(state, memo)
File "C:\Python\lib\copy.py", line 162, in deepcopy
y = copier(x, memo)
File "C:\Python\lib\copy.py", line 254, in _deepcopy_dict
y[deepcopy(key, memo)] = deepcopy(value, memo)
File "C:\Python\lib\copy.py", line 189, in deepcopy
y = _reconstruct(x, rv, 1, memo)
File "C:\Python\lib\copy.py", line 322, in _reconstruct
y = callable(*args)
File "C:\Python\lib\copy_reg.py", line 92, in __newobj__
return cls.__new__(cls, *args)
TypeError: object.__new__(_hashlib.HASH) is not safe, use _hashlib.HASH.__new__()