Correct variable name.

apps/calendar/lib/sabre/object.php

@@ -45,11 +45,11 @@ class OC_Connector_Sabre_CalDAV_CalendarObject extends Sabre_CalDAV_CalendarObje
 		$uid = OC_Calendar_Calendar::extractUserID($this->getOwner());
 
 		if($uid != OCP\USER::getUser()) {
-			$sharedAddressbook = OCP\Share::getItemSharedWithBySource('calendar', $this->$calendarInfo['id']);
-			if ($sharedAddressbook && ($sharedAddressbook['permissions'] & OCP\Share::PERMISSION_READ)) {
+			$sharedCalendar = OCP\Share::getItemSharedWithBySource('calendar', $this->$calendarInfo['id']);
+			if ($sharedCalendar && ($sharedCalendar['permissions'] & OCP\Share::PERMISSION_READ)) {
 				$readprincipal = 'principals/' . OCP\USER::getUser();
 			}
-			if ($sharedAddressbook && ($sharedAddressbook['permissions'] & OCP\Share::PERMISSION_UPDATE)) {
+			if ($sharedCalendar && ($sharedCalendar['permissions'] & OCP\Share::PERMISSION_UPDATE)) {
 				$writeprincipal = 'principals/' . OCP\USER::getUser();
 			}
 		}