Broken in newest Rust version

during compile I get this error: 

```
error[E0432]: unresolved import `std::borrow::IntoCow`
  --> C:\Users\Bertus\.cargo\registry\src\gitlite.zycloud.tk-1ecc6299db9ec823\maybe_utf8
-0.2.3\lib.rs:66:19
   |
66 | use std::borrow::{IntoCow, Cow, ToOwned};
   |                   ^^^^^^^ no `IntoCow` in `borrow`

error: cannot continue compilation due to previous error

```