How to reproduce:
1. Open attached Unity project "zProject_486458"
2. Switch platform to iOS
3. Select BuildTools --> Build AssetBundles
4. Wait until bundles are build
5. Open command-line
6. Run WebExtract <FilePathToSceneBundle>
7. Run binary2text YourSceneBundleName_data/BuildPlayer-SceneBundleName
8. Make a copy of a created text file
9. Close Unity Editor
10. Clear Library and AssetBundles folders
11. Repeat 1-7 steps
12. Compare bundles

Expected result: builds should be identical.
Actual result: builds have differences.

Reproduced with: 2018.1.5f1, 2017.4.5f1, 2017.2.3p1, 5.5.6f1.
Not reproduced with: 2018.3.0a1, 2018.2.0b8, 2017.1.4p1, 5.6.6f2.