Split CONTENT on a line boundary into a prefix smaller than 64k and
        a suffix containing the remainder, omitting the splitting newline.

def _splitBigChunk(self, content, logid):
        """
        Split CONTENT on a line boundary into a prefix smaller than 64k and
        a suffix containing the remainder, omitting the splitting newline.
        """
        # if it's small enough, just return it
        if len(content) < self.MAX_CHUNK_SIZE:
            return content, None

        # find the last newline before the limit
        i = content.rfind(b'\n', 0, self.MAX_CHUNK_SIZE)
        if i != -1:
            return content[:i], content[i + 1:]

        log.msg('truncating long line for log %d' % logid)

        # first, truncate this down to something that decodes correctly
        truncline = content[:self.MAX_CHUNK_SIZE]
        while truncline:
            try:
                truncline.decode('utf-8')
                break
            except UnicodeDecodeError:
                truncline = truncline[:-1]

        # then find the beginning of the next line
        i = content.find(b'\n', self.MAX_CHUNK_SIZE)
        if i == -1:
            return truncline, None
        return truncline, content[i + 1:]