[migration/3.18] Explicitly delete constraint on defaultval
Make sure the SizeConstraint on defaultval is removed, and avoid more
unnecessary commits.
Latest changes
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* table of `all latest changes`_
Links below is providing useful RQL query example.
.. _all latest changes: view?rql=Any+M%2CX+WHERE+X+modification_date+M+ORDERBY+M+DESC+LIMIT+30