How to reproduce:
1. Open the project attached by the user (Bug Report.zip)
2. Open the "BugScene" Scene
3. Observe the error in the console

Expected result: Having an imported Sprite from an old version does not throw the error
Actual result: Having an imported Sprite from an old version throws an error that cannot be fixed in newer versions

Reproducible with: 2017.1.0f1, 2017.1.4f1, 2017.2.3f1, 2017.4.4f1, 2018.1.2f1, 2018.2.0b5

Notes: The error being thrown: "Too many sprite tiles on Image "Panel". The tile size will be increased. To remove the limit on the number of tiles, convert the Sprite to an Advanced texture, remove the borders, clear the Packing tag and set the Wrap mode to Repeat.", cannot be fixed while keeping the same Sprite, as setting a Sprite to an Advanced texture is no longer supported since version 5.5 and onward.