on 1.9 => 2.1 upgrade with oracle 10.2

Error writing to database

More information about this error
Debug info: ORA-01400: cannot insert NULL into ("RESTOREDMOODLEDB"."MDBLOCK_POSITIONS"."SUBPAGE")
INSERT INTO mdblock_positions (blockinstanceid, contextid, pagetype, subpage, visible, region, weight)
SELECT bi.id, bi.contextid,
CASE WHEN bi.pagetypepattern = 'course-view-*'
THEN (SELECT 'course-view-' || c.format
FROM mdcourse c
JOIN mdcontext ctx ON c.id = ctx.instanceid
WHERE ctx.id = bi.contextid)
ELSE bi.pagetypepattern END,
CASE WHEN bi.subpagepattern IS NULL
THEN ''
ELSE bi.subpagepattern END,
0, bi.defaultregion, bi.defaultweight
FROM mdblock_instances bi
WHERE bi.visible = 0 AND bi.pagetypepattern <> 'admin-*' AND bi.pagetypepattern IS NOT NULL
[array (
)]
Stack trace:

• line 396 of /lib/dml/moodle_database.php: dml_write_exception thrown
• line 268 of /lib/dml/oci_native_moodle_database.php: call to moodle_database->query_end()
• line 973 of /lib/dml/oci_native_moodle_database.php: call to oci_native_moodle_database->query_end()
• line 1861 of /lib/db/upgrade.php: call to oci_native_moodle_database->execute()
• line 1417 of /lib/upgradelib.php: call to xmldb_main_upgrade()
• line 277 of /admin/index.php: call to upgrade_core()

for reference:
http://moodle.org/mod/forum/discuss.php?d=180506
http://tracker.moodle.org/browse/MDL-26618 (similar issue)