Reproduction steps:
1. Download and open attached project ("InputTest.zip")
2. Build and run "test.unity" scene on an Android device
3. Connect a mouse to the Android device
4. Press and hold left mouse button
5. While holding left mouse button touch the screen
6. Hold your finger on a screen and release the left mouse button
-- Release your finger off the screen and notice that Input.GetMouseButton(0) stays true

Reproduced with:
2018.2.0a1, 2018.1.0b7, 2017.1.3p1, 5.6.5p2, 5.5.6f1

Devices under testing:
Xiaomi Mi 5s, Android 6.0
Samsung Galaxy Note 8, Android 7.1
Google Pixel 2, Android 8.1
Nexus 7, Android 6.0
HTC One Mini 2, Android 4.4.2