`PathBuf` does not have `is_empty()`

[dhardy]

It is possible to create an empty PathBuf:

let p = PathBuf::new();

— yet PathBuf has no is_empty() function (nor, apparently, do Path or OsStr or OsString).

This seems inconsistent.

Of course, there are several ways around this (p == PathBuf::new(), p.to_str().map_or(true, |s| s.is_empty()), wrapping with Option), but having a simple way to check this would be nice.