Retrieve the most recent commit message (with ``svn info``)

        Returns:
            tuple: (datestr, (revno, user, None, desc))

        $ svn info
        Path: .
        URL: http://python-dlp.googlecode.com/svn/trunk/layercake-python
        Repository Root: http://python-dlp.googlecode.com/svn
        Repository UUID: d0ad5f6e-b329-0410-b51c-492c9c4f233d
        Revision: 378
        Node Kind: directory
        Schedule: normal
        Last Changed Author: chimezie
        Last Changed Rev: 378
        Last Changed Date: 2011-05-01 01:31:38 -0500 (Sun, 01 May 2011)

def __last_commit(self):
        """
        Retrieve the most recent commit message (with ``svn info``)

        Returns:
            tuple: (datestr, (revno, user, None, desc))

        $ svn info
        Path: .
        URL: http://python-dlp.googlecode.com/svn/trunk/layercake-python
        Repository Root: http://python-dlp.googlecode.com/svn
        Repository UUID: d0ad5f6e-b329-0410-b51c-492c9c4f233d
        Revision: 378
        Node Kind: directory
        Schedule: normal
        Last Changed Author: chimezie
        Last Changed Rev: 378
        Last Changed Date: 2011-05-01 01:31:38 -0500 (Sun, 01 May 2011)
        """
        cmd = ['svn', 'info']
        op = self.sh(cmd, shell=False)
        if not op:
            return None
        author, rev, datestr = op.split('\n')[7:10]
        author = author.split(': ', 1)[1].strip()
        rev = rev.split(': ', 1)[1].strip()
        datestr = datestr.split(': ', 1)[1].split('(', 1)[0].strip()
        return datestr, (rev, author, None, None)