Model importer cannot be scripted to fill in the Avatar for animations without errors or manual work. User has to take the extra step of pressing "Update" in the model import settings to make it work. This is really not ideal as it bars the possibility of fully automating this process.

Reproduction steps:
1. Open the attached project.
2. Open "AnimationPostProcessor.cs" in the “Scripts” -folder and set "variable_case2" to true.
3. Reimport "@Idle_Case2_Anim.fbx" from inside of the “Animation” -folder (Right mouse button > Reimport).
4. Observe the Inspector Import Settings view.

Actual result:
- There will be Errors(s) found. If the user clicks on the Update -button, the problem will be fixed, but this step cannot be automated through script, requiring manual work by the user.

Expected result:
- The file should now use the assigned Human Avatar from another file.

Note:
- The problem persists on Generic avatars also, it will prompt the update button on the import settings but without giving any errors.

Reproduced with:
2017.1.5f1, 2017.2.3p2, 2017.4.8f1, 2018.1.9f1, 2018.2.1f1, 2018.3.0a6