chore: checkpoint before Python removal

vendor/bytes/src/fmt/hex.rs

@@ -0,0 +1,27 @@
+use core::fmt::{Formatter, LowerHex, Result, UpperHex};
+
+use super::BytesRef;
+use crate::{Bytes, BytesMut};
+
+impl LowerHex for BytesRef<'_> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+        for &b in self.0 {
+            write!(f, "{:02x}", b)?;
+        }
+        Ok(())
+    }
+}
+
+impl UpperHex for BytesRef<'_> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+        for &b in self.0 {
+            write!(f, "{:02X}", b)?;
+        }
+        Ok(())
+    }
+}
+
+fmt_impl!(LowerHex, Bytes);
+fmt_impl!(LowerHex, BytesMut);
+fmt_impl!(UpperHex, Bytes);
+fmt_impl!(UpperHex, BytesMut);