bpo-35036: Use empty message as default for logger

[tirkarthi]

This fixes the change introduced in ee171a2 where self.info() was replaced with self.logger.info() . self.info was deprecated but it had a default of message='' and the new change also follows the same. I think this is a no-op and can be removed but that is subjected to approval from the reviewer.

Original self.info definition :

def info(self, message='', nonl=False):
    # type: (unicode, bool) > None
    """Emit an informational message.

    If *nonl* is true, don't emit a newline at the end (which implies that
    more info output will follow soon.)

    .. deprecated:: 1.6
       Use :mod:`sphinx.util.logging` instead.
    """
    warnings.warn('app.info() is now deprecated. Use sphinx.util.logging instead.',
                  RemovedInSphinx20Warning)
    logger.info(message, nonl=nonl)

https://bugs.python.org/issue35036

[tirkarthi]

cc @pablogsal for review

[pablogsal]

Thanks for the catch and the PR!

[pablogsal]

I have pushed to your branch removing the logline, as it is not doing anything and can be safely deleted.

[tirkarthi]

Sure, thanks for merging it :)

[miss-islington]

Thanks @tirkarthi for the PR, and @pablogsal for merging it 🌮🎉.. I'm working now to backport this PR to: 2.7.
🐍🍒⛏🤖

[bedevere-bot]

GH-16637 is a backport of this pull request to the 2.7 branch.