When a project path contains non-ASCII characters, virtualized asset paths are incorrectly computed and this seems to trip the Asset Database when importing packaged assets, resulting in warnings "A meta data file (.meta) exists but its asset 'Packages/com.unity.purchasing.6/License.md' can't be found. When moving or deleting files outside of Unity, please ensure that the corresponding .meta file is moved or deleted along with it."

This issue was investigated a while ago (for some reason, no Issue was created) and it seemed at the time to be a problem in the VFS remapping (or rather, code that uses it), when the following information are combined:
- The absolute path of the package (e.g. /Users/maximeb/UnityProjects/été/Library/PackageCache/com.unity.purchasing@2.0.6
- The package mount point/redirect point (e.g. Packages/com.unity.purchasing)
- The relative asset path under the package (e.g. package.json)

Repro Steps:
1) Create a project named "été" (no quotes)

Expected: The project created successfully with default packages, and all packages load properly
Actual: None of the packaged assets (except from built-in packages) are loaded properly. A wall of warnings notes that the asset cannot be found, but the path is incorrect (there should be no trailing ".<number>" after the package name in the path.

Workaround: don't use accents or "extended ASCII" or non-ASCII Unicode characters in the project path.

Reproduced in: 2018.4.6f1, 2018.4.9f1, 2019.1.10f1, 2019.1.14f1, 2019.2.6f1 (only tested ADB V1 in all cases)
Not reproduced in: 2019.3.0b4 (both ADB V1 and V2), 2020.1.0a3