Detailed revision comments:

r6673 | marko | 2010-02-11 13:09:48 +0200 (Thu, 11 Feb 2010) | 9 lines
branches/zip: Relax a debug assertion about a missing BLOB. (Issue #452)
When rolling back an incomplete transaction in purge, tolerate missing
BLOBs also in update undo, when undoing an INSERT by updating a delete-marked
record, and the delete-marked record is no longer needed.
Previously, we only tolerated missing BLOBs in insert undo.
This merely fixes a debug assertion; the code performed correctly
without UNIV_DEBUG.

rb://249 approved by Sunny Bains.