think about Item.path == "." special case

[ThomasWaldmann]

see code and discussion of PR #7108.

• the sanitize code might return "." for some edge cases. in some exotic cases maybe even to "just return something" (e.g. if return value would be "" or ".." otherwise).
• a user also might feed in "." somehow (cli, via --paths-from-stdin).

but I guess borg can't really restore a "." directory item right now:

• borg usually removes existing directories of same name before extracting them from an archive - can it remove "."? needs checking.
• it could make sense maybe to get the metadata of that item restored.