Revert wrong item.thr-parent field usage in Protocol\OStatus

src/Protocol/OStatus.php

@@ -523,7 +523,7 @@ class OStatus
 					}
 				} else {
 					// But we will only import complete threads
-					$valid = Item::exists(['uid' => $importer["uid"], 'uri' => self::$itemlist[0]['thr-parent']]);
+					$valid = Item::exists(['uid' => $importer["uid"], 'uri' => self::$itemlist[0]['parent-uri']]);
 					if ($valid) {
 						Logger::log("Item with uri ".self::$itemlist[0]["uri"]." belongs to parent ".self::$itemlist[0]['thr-parent']." of user ".$importer["uid"].". It will be imported.", Logger::DEBUG);
 					}