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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def update_context(self):
 """ Make sure Bazaar respects the configured author. This method first calls :func:`.Repository.update_context()` and then it sets the ``$BZR_EMAIL`` environment variable based on the value of :attr:`~Repository.author` (but only if :attr:`~Repository.author` was set by the caller). This is a workaround for a weird behavior of Bazaar that I've observed when running under Python 2.6: The ``bzr commit --author`` command line option is documented but it doesn't prevent Bazaar from nevertheless reporting the following error:: bzr: ERROR: Unable to determine your name. Please, set your name with the 'whoami' command. E.g. bzr whoami "Your Name <name@example.com>" """

        # Call our superclass.
        super(BzrRepo, self).update_context()
        # Try to ensure that $BZR_EMAIL is set (see above for the reason)
        # but only if the `author' property was set by the caller (more
        # specifically there's no point in setting $BZR_EMAIL to the
        # output of `bzr whoami').
        if self.__dict__.get('author'):
            environment = self.context.options.setdefault('environment', {})
            environment.setdefault('BZR_EMAIL', self.author.combined)