Store whether a result is provisional before filtering it

Filtering returns a new array, which was clobbering the "provisional" flag.
This was causing provisionally results to not be reprocessed later,
which meant that certain "outdated_tags" results would not be in the baseCache.
(cache of issues _before_ user edits).

modules/core/validator.js

@@ -547,10 +547,11 @@ export function coreValidator(context) {
         return;
       }
 
-      const detected = fn(entity, graph).filter(applySeverityOverrides);
+      let detected = fn(entity, graph);
       if (detected.provisional) {  // this validation should be run again later
         result.provisional = true;
       }
+      detected = detected.filter(applySeverityOverrides);
       result.issues = result.issues.concat(detected);
     }