Cache would not store the downloaded data if the cached file already existed. Remove old one first

@@ -185,7 +185,12 @@ static NSString *permanentCacheFolder = @"PermanentStore";
 		[[request responseData] writeToFile:dataPath atomically:NO];
 	} else if ([request downloadDestinationPath] && ![[request downloadDestinationPath] isEqualToString:dataPath]) {        
 		NSError *error = nil;
-		[[[[NSFileManager alloc] init] autorelease] copyItemAtPath:[request downloadDestinationPath] toPath:dataPath error:&error];
+        NSFileManager* manager = [[NSFileManager alloc] init];
+        if ([manager fileExistsAtPath:dataPath]) {
+            [manager removeItemAtPath:dataPath error:&error];
+        }
+        [manager copyItemAtPath:[request downloadDestinationPath] toPath:dataPath error:&error];
+        [manager release];
 	}
 	[[self accessLock] unlock];
 }