To reproduce:

1. Download attached project "ReadLocalAndroid_2017.3.1p4.zip" and open in Unity
2. Open "TestScene" scene
3. Run logcat
4. Build and Run the project on a Device
5. Observe logcat

Expected results: In logcat you see a bunch of Tests. For example:

============ Test 按英文字母顺序 =====================
04-11 15:22:18.782 6238 6255 I Unity : [path]jar:file:///data/app/com.readlocal.test-IYmBELViWuPO-0L4maPO0g==/base.apk!/assets/按英文字母顺序.txt
04-11 15:22:18.797 6238 6255 I Unity : [downaloded bytes]13
04-11 15:22:18.797 6238 6255 I Unity : [contents]ABCD大中国
04-11 15:22:18.800 6238 6255 I Unity :
04-11 15:22:18.800 6238 6255 I Unity : [uri]jar:file:/data/app/com.readlocal.test-IYmBELViWuPO-0L4maPO0g==/base.apk!/assets/按英文字母顺序.txt
04-11 15:22:18.814 6238 6255 I Unity : [downaloded bytes]13
04-11 15:22:18.815 6238 6255 I Unity : [contents]ABCD大中国

Actual results: In logcat you see a bunch of Tests. For example:

============ Test 按英文字母顺序 =====================
04-11 13:26:51.097 1599 1618 I Unity : [path]jar:file:///data/app/com.readlocal.test--d2xWrqEDuRlioACWAV4NQ==/base.apk!/assets/按英文字母顺序.txt
04-11 13:26:51.112 1599 1618 I Unity : [downaloded bytes]0
04-11 13:26:51.123 1599 1618 E Unity : [error]Generic/unknown HTTP error
04-11 13:26:51.123 1599 1618 E Unity : UnityEngine.DebugLogHandler:Internal_Log(LogType, String, Object)
04-11 13:26:51.123 1599 1618 E Unity : UnityEngine.DebugLogHandler:LogFormat(LogType, Object, String, Object[])
04-11 13:26:51.123 1599 1618 E Unity : UnityEngine.Logger:Log(LogType, Object)
04-11 13:26:51.123 1599 1618 E Unity : UnityEngine.Debug:LogError(Object)
04-11 13:26:51.123 1599 1618 E Unity : <TestCoroutine>c__Iterator1:MoveNext() (at C:\Users\Jonas\Desktop\1021238\Assets\TestScript.cs:35)
04-11 13:26:51.123 1599 1618 E Unity : UnityEngine.SetupCoroutine:InvokeMoveNext(IEnumerator, IntPtr) (at /Users/builduser/buildslave/unity/build/Runtime/Export/Coroutines.cs:17)
04-11 13:26:51.123 1599 1618 E Unity :
04-11 13:26:51.123 1599 1618 E Unity : (Filename: C Line: 0)
04-11 13:26:51.123 1599 1618 E Unity :
04-11 13:26:51.124 1599 1618 I Unity :
04-11 13:26:51.124 1599 1618 I Unity : [uri]jar:file:/data/app/com.readlocal.test--d2xWrqEDuRlioACWAV4NQ==/base.apk!/assets/按英文字母顺序.txt
04-11 13:26:51.145 1599 1618 I Unity : [downaloded bytes]13
04-11 13:26:51.145 1599 1618 I Unity : [contents]ABCD大中国

Notes:
- Logcats are shared in the comments section
- On iOS, this issue reproduces too
- In Windows and OSX standalone everything works fine

Devices:
- Google Pixel 2, OS: 8.1.0, CPU: arm64-v8a, GPU: Adreno (TM) 540
- iPhone 7, iOS: 11.2.6, CPU: A10

Reproduced on Unity 2017.3.1p3, 2017.3.2f1, 2017.4.1f1, 2018.1.0f1 and 2018.2.0a9
Not reproduced on Unity 2017.3.1p2
Regression on Unity 2017.3.1p3

Fixed in: 2017.4.5f1, 2018.1.3f1, 2018.2.0b4, 2018.3.0a1