Steps to reproduce:
1. Start a new project in a directory named with other language characters (example: Jää-Aro)
2. Try to save the scene
3. Observe the message "Save the scene in the Assets folder" even though it is saved in the Assets folder

Expected result: when the project directory is named with characters of other languages, you should still be able to save the scene

Reproduced on Unity 2017.2.0a3, 2017.1.0b8, 5.6.1p3, 5.5.4f1, 5.4.5p2
Reproduced in OS X 10.10.2, 10.9.5