Backup fails when save folder/directory is a symbolic link

The bug

When using the "backup" option for a world, I get "backup failed" if the world is a symbolic link in the saves/ folder. This is on win7x64.

How to reproduce

1. I had a 1.16 snapshot world last played with 20w22a
2. I upgrade to 1.16 pre1
3. I select my 1.16 world in the game with the 'edit' option so I can make a backup
4. I click 'backup' and I get the 'backup failed' error message