python-asteval fails to build with Python 3.9.0a5.

___________________________ TestEval.test_dict_index ___________________________

self = <test_asteval.TestEval testMethod=test_dict_index>

    def test_dict_index(self):
        """dictionary indexing"""
        self.interp("a_dict = {'a': 1, 'b': 2, 'c': 3, 'd': 4}")
>       self.istrue("a_dict['a'] == 1")

tests/test_asteval.py:141: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
tests/test_asteval.py:105: in istrue
    return self.assertTrue(val)
E   AssertionError: False is not true
___________________________ TestEval.test_list_index ___________________________

self = <test_asteval.TestEval testMethod=test_list_index>

    def test_list_index(self):
        """list indexing"""
        self.interp("a_list = ['a', 'b', 'c', 'd', 'o']")
>       self.istrue("a_list[0] == 'a'")

tests/test_asteval.py:147: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
tests/test_asteval.py:105: in istrue
    return self.assertTrue(val)
E   AssertionError: False is not true
____________________________ TestEval.test_minimal _____________________________

self = <test_asteval.TestEval testMethod=test_minimal>

    def test_minimal(self):
        aeval = Interpreter(builtins_readonly=True, minimal=True)
        aeval("a_dict = {'a': 1, 'b': 2, 'c': 3, 'd': 4}")
>       self.assertTrue(aeval("a_dict['a'] == 1"))
E       AssertionError: False is not true

tests/test_asteval.py:1024: AssertionError
______________________________ TestEval.test_repr ______________________________

self = <test_asteval.TestEval testMethod=test_repr>

    def test_repr(self):
        """repr of dict, list"""
        self.interp("x = {'a': 1, 'b': 2, 'c': 3}")
        self.interp("y = ['a', 'b', 'c']")
        self.interp("rep_x = repr(x['a'])")
        self.interp("rep_y = repr(y)")
        self.interp("rep_y , rep_x")
        self.interp("repr(None)")
>       self.isvalue("rep_x", "1")

tests/test_asteval.py:360: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <test_asteval.TestEval testMethod=test_repr>, sym = 'rep_x', val = '1'

    def isvalue(self, sym, val):
        """assert that a symboltable symbol has a particular value"""
        tval = self.interp.symtable[sym]
        if HAS_NUMPY and isinstance(val, np.ndarray):
            assert_allclose(tval, val, rtol=0.01)
        else:
>           assert(tval == val)
E           AssertionError: assert 'None' == '1'
E             - None
E             + 1

tests/test_asteval.py:91: AssertionError
__________________________ TestEval.test_string_index __________________________

self = <test_asteval.TestEval testMethod=test_string_index>

    def test_string_index(self):
        """string indexing"""
        self.interp("a_string = 'hello world'")
>       self.istrue("a_string[0] == 'h'")

tests/test_asteval.py:160: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
tests/test_asteval.py:105: in istrue
    return self.assertTrue(val)
E   AssertionError: False is not true
__________________________ TestEval.test_tuple_index ___________________________

self = <test_asteval.TestEval testMethod=test_tuple_index>

    def test_tuple_index(self):
        """tuple indexing"""
        self.interp("a_tuple = (5, 'a', 'x')")
>       self.istrue("a_tuple[0] == 5")

tests/test_asteval.py:154: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
tests/test_asteval.py:105: in istrue
    return self.assertTrue(val)
E   AssertionError: False is not true
===================== 6 failed, 52 passed in 1.17 seconds ======================

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.9/fedora-rawhide-x86_64/01324205-python-asteval/

For all our attempts to build python-asteval with Python 3.9, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.9/package/python-asteval/

Testing and mass rebuild of packages is happening in copr. You can follow these instructions to test locally in mock if your package builds with Python 3.9:
https://copr.fedorainfracloud.org/coprs/g/python/python3.9/

Let us know here if you have any questions.

Python 3.9 will be included in Fedora 33. To make that update smoother, we're building Fedora packages with early pre-releases of Python 3.9.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires), so if this package is required a lot, it's important for us to get it fixed soon.
We'd appreciate help from the people who know this package best, but if you don't want to work on this now, let us know so we can try to work around it on our side.