diff -r b4e7099ea2f1 -r 62c880e5d980 misc/migration/3.10.9_Any.py
--- a/misc/migration/3.10.9_Any.py	Mon Mar 21 17:44:57 2011 +0100
+++ b/misc/migration/3.10.9_Any.py	Thu Mar 24 13:24:26 2011 +0100
@@ -1,10 +1,11 @@
 from __future__ import with_statement
 import sys
 
-# fix some corrupted entities noticed on several instances
-rql('DELETE CWConstraint X WHERE NOT E constrained_by X')
-rql('SET X is_instance_of Y WHERE X is Y, NOT X is_instance_of Y')
-commit()
+
+if confirm('fix some corrupted entities noticed on several instances?'):
+    rql('DELETE CWConstraint X WHERE NOT E constrained_by X')
+    rql('SET X is_instance_of Y WHERE X is Y, NOT X is_instance_of Y')
+    commit()
 
 if confirm('fix existing cwuri?'):
     from logilab.common.shellutils import ProgressBar