Detailed revision comments:

r6321 | marko | 2009-12-16 16:16:33 +0200 (Wed, 16 Dec 2009) | 4 lines
branches/zip: row_merge_drop_temp_indexes(): Revert a hack to
transaction isolation level that was made unnecessary by r5826 (Issue #337).
When this function is called, any active data dictionary transaction
should have been rolled back.