cubicweb #6510918 sync_schema sometimes does not do the job [validation pending]

such as updating a static vocabulary

this happens whenever someone issues a sync_schema('foo', syncprops=False)
and later a sync_schema('foo')

priorityimportant
typebug
done in3.19.13
load1.000
load left0.000
closed by#743ed2b13a6f [syncschema] only add to the `synchronized` set if all possible updates have been done
patch[syncschema] only add to the `synchronized` set if all possible updates have been done [applied]