traceback is lost when using Promise.all

[lexdene]

the following code:

from promise import Promise

def foo(v):
    if v == 4:
        raise ValueError(v)

    return v + 1

def main():
    p = Promise.all([
        Promise.promisify(foo)(number)
        for number in range(5)
    ])
    p.get()

main()

I think its traceback should be like this:

Traceback (most recent call last):
  File ".../venv/promise/promise.py", line 500, in _resolve_from_executor
    executor(resolve, reject)
  File ".../venv/promise/promise.py", line 770, in executor
    return resolve(f(*args, **kwargs))
File "foo.py", line 6, in foo
    raise ValueError(v)
ValueError: 4

Actually its traceback is:

Traceback (most recent call last):
  File "foo.py", line 16, in <module>
    main()
  File "foo.py", line 14, in main
    p.get()
  File ".../venv/promise/promise.py", line 526, in get
    return self._target_settled_value(_raise=True)
  File ".../venv/promise/promise.py", line 530, in _target_settled_value
    return self._target()._settled_value(_raise)
  File ".../venv/promise/promise.py", line 235, in _settled_value
    reraise(type(raise_val), raise_val, self._traceback)
  File "<string>", line 3, in reraise
ValueError: 4

It makes me hard to debug when error happens.