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
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"""
"""
Keeps information about historical releases.
"""
ReleaseInfo = collections.namedtuple(
    "ReleaseInfo",
    "release_version release_version_no_leading_zeros last_commit_hash content file_name")
def strip_leading_zeros_in_calver(calver_version: str) -> str:
    """
    Strips leading zeros from calver version number.
    This converts 1974.04.03 to 1974.4.3 as the format with leading month and day zeros is not accepted
    by PIP versioning.
    :param calver_version: version number in calver format (potentially with leading 0s in date and month)
    :return: string with leading 0s after dot replaced.
    """
    return calver_version.replace(".0", ".")
def get_provider_changes_prefix(backport_packages: bool) -> str: