Use "git tag -l" to get tag message contents
Use "git tag -l" to get tag message contents

The code that splits the message when a line starts with
"commit " breaks when the actual tag message contains a line
starting with "commit ".  Using "git tag -l --format=%(message)"
will avoid that problem.

As "git tag -l" won't error out if the tag doesn't exist, now we
can just use _git() instead of ignoring stderr.

Signed-off-by: Eduardo Habkost <50373d7c08ceadf576dd7dca718012445b677ce6@redhat.com>

stefanha/git-publish,stefanha/git-publish