When a project gets imported with dlls that don't have valid PluginImporter settings, the metafile gets written back to disk with changes.

How to reproduce:
- Unzip Plugins.zip on your computer.
- Copy/Paste the Plugins folder in a new Unity project.
- Open/focus back Unity so it imports the Plugins folder
- Compare Plugins/x86_64/abci.bundle.meta with the one from the zip file.

Actual: The metafile changed.
Expected: Metafiles should never change until users perform explicit changes to the importer settings.