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
backport_packages: bool) -> Tuple[str, Optional[str]]:
    """
    Check if the release version passed is not later than the last release version
    :param past_releases: all past releases (if there are any)
    :param current_release_version: release version to check
    :param backport_packages: whether to prepare regular (False) or backport (True) packages
    :return: Tuple of current/previous_release (previous might be None if there are no releases)
    """
    previous_release_version = past_releases[0].release_version if past_releases else None
    if current_release_version == '':
        if previous_release_version:
            current_release_version = previous_release_version
        else:
            if backport_packages:
                current_release_version = (datetime.today() + timedelta(days=5)).strftime('%Y.%m.%d')
            else:
                current_release_version = "0.0.1"  
    if previous_release_version:
        if backport_packages:
            if previous_release_version > current_release_version:
                print(f"The release {current_release_version} must be not less than "
                      f"{previous_release_version} - last release for the package", file=sys.stderr)
                sys.exit(2)
        else:
            if semver.compare(previous_release_version, current_release_version) > 0:
                print(f"The release {current_release_version} must be not less than "
                      f"{previous_release_version} - last release for the package", file=sys.stderr)
                sys.exit(2)
    return current_release_version, previous_release_version
def get_cross_provider_dependent_packages(provider_package_id: str) -> List[str]: