Can't search message with special symbol like "\","/","<",">".

[XvTianYuan]

Expected behavior

A contact contains message like "><" or "/".
Then the user should search this message successfully.

Actual behavior

User can not search these kind of message.

Steps to reproduce

1. select a chat and send message with special symbol only.
2. search the message you just sended.

Environment

Kontalk version: 4.4.0 (F-Droid)

Android version: Android 8.1.0

Device model: Virtual Device Pixel 2 API 27