rust-hg-path: implement `Display` for `HgPath` and `HgPathBuf`

This is useful when debugging, to get a human readable output instead of an
array of `u8`.

Differential Revision: https://phab.mercurial-scm.org/D7523

rust/hg-core/src/utils/hg_path.rs

@@ -7,6 +7,7 b''
 
 use std::borrow::Borrow;
 use std::ffi::{OsStr, OsString};
+use std::fmt;
 use std::ops::Deref;
 use std::path::{Path, PathBuf};
 
@@ -162,6 +163,12 b' impl HgPath {'
     }
 }
 
+impl fmt::Display for HgPath {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", String::from_utf8_lossy(&self.inner))
+    }
+}
+
 #[derive(Eq, Ord, Clone, PartialEq, PartialOrd, Debug, Hash)]
 pub struct HgPathBuf {
     inner: Vec<u8>,
@@ -185,6 +192,12 b' impl HgPathBuf {'
     }
 }
 
+impl fmt::Display for HgPathBuf {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", String::from_utf8_lossy(&self.inner))
+    }
+}
+
 impl Deref for HgPathBuf {
     type Target = HgPath;