{node}.body and {node}.teaser should be nullable

- Set up a content type that doesn't use 'body' field
- create a node of this content type
- edit the node, check 'create a new revision' checkbox, save :

PDOException: INSERT INTO {node_revision} (nid, uid, title, teaser, log, timestamp, format) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6) - Array ( [:db_insert_placeholder_0] => 1 [:db_insert_placeholder_1] => 1 [:db_insert_placeholder_2] => article1 [:db_insert_placeholder_3] => [:db_insert_placeholder_4] => [:db_insert_placeholder_5] => 1230853018 [:db_insert_placeholder_6] => 0 ) SQLSTATE[HY000]:
General error: 1364 Field 'body' doesn't have a default value in drupal_write_record() (line 3798 \includes\common.inc).

Attached patch makes the body and teaser columns nullable in node_revision table (as suggested in a comment in node_save).