The dependencies in Alphas are currently >= 2.0.0 and should be >=2.0.0a0 in order to work with Alphas in cases which are not PEP 440-compliant.

According to https://www.python.org/dev/peps/pep-0440/, >= 2.0.0 should also work with alpha/beta releases (a1/a2) but in some cases it does not (https://apache-airflow.slack.com/archives/C0146STM600/p1602774750041800) 

Changing to ">=2.0.0a0" should help.
provider_packages/setup_provider_packages.py
"""
    Is the class imported from another module?
    :param the_class: the class object itself
    :param imported_name: name of the imported class
    :return: true if the class was imported from another module
    """
    return ".".join(imported_name.split(".")[:-1]) == the_class.__module__
def is_example_dag(imported_name: str) -> bool:
    """
    Is the class an example_dag class?
    :param imported_name: name where the class is imported from
    :return: true if it is an example_dags class
    """
    return ".example_dags." in imported_name
def is_from_the_expected_base_package(the_class: Type, expected_package: str) -> bool: