bugz

Fixes #97.
Fixes #96.

Needs:

```sql
DROP PROCEDURE IF EXISTS paste_put@@
CREATE PROCEDURE paste_put (
  p_secret BINARY(16),
  p_content MEDIUMBLOB,
  OUT p_id MEDIUMINT,
  OUT p_digest BINARY(20),
  OUT p_label TINYBLOB
)
BEGIN
  START TRANSACTION;
  UPDATE paste
  SET digest = UNHEX(SHA1(p_content)), content = p_content
  WHERE secret = p_secret;
  UPDATE private
  SET digest = UNHEX(SHA1(p_content)), content = p_content
  WHERE secret = p_secret;
  UPDATE vanity
  SET digest = UNHEX(SHA1(p_content)), content = p_content
  WHERE secret = p_secret;
  /* .. */
  SELECT id INTO p_id
  FROM paste
  WHERE secret = p_secret;
  SELECT digest INTO p_digest
  FROM private
  WHERE secret = p_secret;
  SELECT label INTO p_label
  FROM vanity
  WHERE secret = p_secret;
  COMMIT;
END;
@@
```