By default, git does not fetch tags on a checkout, so fetch those when
building a tag.
When the tags are not fetched and building master, both HIGHEST and
LATEST_TAG were "", which was equal. Thus, every master push was tagged
as latest. This is now handled correctly.
Signed-off-by: Nolan Brubaker <brubakern@vmware.com>
132f1fd3a8