Updating a project to a new editor version sometime causes immutable assets to be altered.

Steps to reproduce:

1) Create a new Unity project from the 3D template.

2) Close the editor.

3) Open the project with a more recent editor version.

Actual Result: A warning is displayed in the console with a list of modified immutable assets.

Expected Result: No warnings are displayed in the console.

Reproduced in 2020.1.0b12, 2020.1.0b14