Returns the name of module corresponding to 'jamfile-location'.
        If no module corresponds to location yet, associates default
        module name with that location.

def module_name(self, jamfile_location):
        """Returns the name of module corresponding to 'jamfile-location'.
        If no module corresponds to location yet, associates default
        module name with that location."""
        assert isinstance(jamfile_location, basestring)
        module = self.location2module.get(jamfile_location)
        if not module:
            # Root the path, so that locations are always umbiguious.
            # Without this, we can't decide if '../../exe/program1' and '.'
            # are the same paths, or not.
            jamfile_location = os.path.realpath(
                os.path.join(os.getcwd(), jamfile_location))
            module = "Jamfile<%s>" % jamfile_location
            self.location2module[jamfile_location] = module
        return module