cubicweb-dataio #3524192 Do not reapply indexes if the dataio_constraints table does not exist [validation pending]

There may be an error as the table dataio_constraints does not exist, and we search for indexes in it. We should also raise a Warning.

prioritynormal
typebug
done in0.4.1
load0.200
load left0.000
closed by#e6b5b1f8e934 [dataimport] Do not reapply indexes if the dataio_constraints table does not exist, closes #3524192
patch[dataimport] Do not reapply indexes if the dataio_constraints table does not exist, closes #3524192 [applied]