def delete_post_replies(post_id):
    """Delete ALL comments on post with pid.

    This can't be done in one single call to Mongo because we need to remove
    the votes from Redis!

    """
    # Get a cursor for all the posts comments
    cur = m.db.posts.find({'reply_to': post_id})

    # Iterate over the cursor and delete each one
    for reply in cur:
        reply_id = reply.get('_id')

        # Delete the comment itself from MongoDB
        m.db.posts.remove({'_id': reply_id})

        # Remove any uploaded files
        if 'upload' in reply:
            storage.delete(reply['upload'])

        # Delete votes from Redis
        r.delete(k.POST_VOTES.format(reply_id))