[BUGFIX] Skip event-transforming DataHandlerInterceptor while importing

In case `ext:impexp` is importing, the interceptor is skipped.

Classes/DataHandling/Interceptor/Hook/Backend/DataHandlerHook.php

@@ -34,9 +34,15 @@ public function processCmdmap_beforeStart(DataHandler $dataHandler)
 
     protected function process(DataHandler $dataHandler)
     {
+        // skip, in case there's actually nothing to do
         if (empty($dataHandler->datamap) && empty($dataHandler->cmdmap)) {
             return;
         }
+        // skip, in case this is an import process
+        // @todo `ext:impexp` still should be handled at some point (later™)
+        if ($dataHandler->isImporting) {
+            return;
+        }
         // create command mapper for incoming data
         $commandTranslator = DataHandlerTranslator::create(
             $dataHandler->datamap,