To reproduce:

1. Download attached project "MeshPrecision.zip" and open in Unity
2. Open "SampleScene" scene
3. Click Window > AssetBundles Browser
4. Press "Build" button in "Build" tab
5. Inspect "terrainmesh_0_1_0" gameObject and all his child's to see that them Rotation are 0, 0, 0
6. Enter Play mode
7. Observe "terrainmesh_0_1_0(Clone)" gameObject and all his child's

Expected results: "terrainmesh_0_1_0(Clone)" gameObject and all his child's Rotation are 0, 0, 0
Actual results: "terrainmesh_0_1_0(Clone)" gameObject and all his child's Rotation are random numbers

Notes:
- This issue is reproduced on both Windows and OSX
- Video of reproduction of this bug is in Comments section
- Sometimes you need to build asset bundle multiple times to reproduce the bug, and every time it changes to a different value

Reproduced on Unity 2017.1.0a4, 2017.1.4f1, 2017.2.3f1, 2017.3.2f1, 2017.4.4f1, 2018.1.2f1, 2018.2.0b5 and 2018.3.0a1
Not reproduced on Unity 2017.1.0a3
Regression on Unity 2017.1.0a4