Some of the older released versions of projects don't work when we run
'python setup.py --name' (disk-image-builder was the main one I
noticed). This patch protects against those exceptions, and reports them
as warnings if the release is already tagged and errors if it is a new
release.
Change-Id: Iaa47e7ea2a52efee200e8c710c3660a7893b5147
Signed-off-by: Doug Hellmann <doug@doughellmann.com>