To reproduce:

1. Download and open attached "test_android.zip" project.
2. Go to Build Settings and build the apk.
3. Extract built apk file to see its contents.
4. Go to extracted folder and then open "assets" folder.
5. Notice the files which are in assets folder.

Actual result: gunzipped (.gz) archive is forcefully extracted after apk is built with archive being in StreamingAssets folder.
Expected result: After build, all archives which are in StreamingAssets folder do not change their initial state. None of them are extracted.

Reproduced with: 2017.2.0b1, 2017.1.0f2, 5.6.2f1, 5.5.4f1, 5.4.5p3, 5.3.8f1, 5.2.3p3.

Notes: Does not repro on iOS and Standalone. Issue persists with both scripting backends (mono and IL2CPP).