Pierre-Yves David <pierre-yves.david@logilab.fr> [Thu, 28 Mar 2013 11:45:17 +0100] rev 8818
[migration] fix bug in `CWAttributeAddOp.revertprecommit_event`
The `rdefdef` attribute is set during the operation execution. In some the
operation crash before this assignment. In such case `revertprecommit` raise an
attribute error crashing the whole process and shadowing the original error.
This changeset detect and Avoid this situation.