Non standard characters getting filtered

This bug was first mentioned, in the Swedish Drupal Group, by rtauson.

Uploading a file called åäö.txt (Swedish letters) results in the file getting renamed to 'txt.'. The expected filename would 'åäö.txt' (ie. unchanged). The good thing is that the link to the file still works so this is not critical.

At first I thought the upload.core module filtered out non-[A-z]-letters but uploading a file named 'Bokstaven å va dä på en ö sa han.txt' yielded an uploaded file with the exact same name (and with a linked that worked perfectly).

One workaround that currently works is to use Translitteration, mentioned here (in Swedish).