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
past_releases: List[ReleaseInfo],
                              current_release_version: str) -> Optional[str]:
    """
    Find previous release. In case we are re-running current release we assume that last release was
    the previous one. This is needed so that we can generate list of changes since the previous release.
    :param previous_release_version: known last release version
    :param past_releases: list of past releases
    :param current_release_version: release that we are working on currently
    :return:
    """
    previous_release = None
    if previous_release_version == current_release_version:
        
        if len(past_releases) > 1:
            previous_release = past_releases[1].last_commit_hash
    else:
        previous_release = past_releases[0].last_commit_hash if past_releases else None
    return previous_release
def check_if_release_version_ok(
        past_releases: List[ReleaseInfo],
        current_release_version: str,