D6593: rust-minor-fixes: remove Deref in favor of explicit methods

[Yuya Nishihara]

>   Using `keys()` will change the behavior, as I actually need to expose an `Iter<Vec<u8>, u32>`. Is your issue with the naming?

No. My point is that the refcount value is an implementation detail.
Do you have some plan to use the refcount value?

```
diff --git a/rust/hg-core/src/dirstate/dirs_multiset.rs b/rust/hg-core/src/dirstate/dirs_multiset.rs
--- a/rust/hg-core/src/dirstate/dirs_multiset.rs
+++ b/rust/hg-core/src/dirstate/dirs_multiset.rs
@@ -8,7 +8,7 @@
 //! A multiset of directory names.
 //!
 //! Used to counts the references to directories in a manifest or dirstate.
-use std::collections::hash_map::{Entry, Iter};
+use std::collections::hash_map::{Entry, Keys};
 use std::collections::HashMap;
 use {DirsIterable, DirstateEntry, DirstateMapError};
 
@@ -128,8 +128,8 @@ impl DirsMultiset {
         self.inner.contains_key(key)
     }
 
-    pub fn iter(&self) -> Iter<Vec<u8>, u32> {
-        self.inner.iter()
+    pub fn iter(&self) -> Keys<Vec<u8>, u32> {
+        self.inner.keys()
     }
 
     pub fn len(&self) -> usize {
diff --git a/rust/hg-cpython/src/dirstate.rs b/rust/hg-cpython/src/dirstate.rs
--- a/rust/hg-cpython/src/dirstate.rs
+++ b/rust/hg-cpython/src/dirstate.rs
@@ -271,20 +271,9 @@ py_class!(pub class Dirs |py| {
     // of having it work to continue working on the rest of the module
     // hopefully bypassing Python entirely pretty soon.
     def __iter__(&self) -> PyResult<PyObject> {
-        let dict = PyDict::new(py);
-
-        for (key, value) in self.dirs_map(py).borrow().iter() {
-            dict.set_item(
-                py,
-                PyBytes::new(py, &key[..]),
-                value.to_py_object(py),
-            )?;
-        }
-
-        let locals = PyDict::new(py);
-        locals.set_item(py, "obj", dict)?;
-
-        py.eval("iter(obj)", None, Some(&locals))
+        // maybe there would be a better way to cast objects back and forth?
+        let dirs: Vec<_> = self.dirs_map(py).borrow().iter().map(|d| PyBytes::new(py, d)).collect();
+        dirs.to_py_object(py).into_object().iter(py).map(|o| o.into_object())
     }
 
     def __contains__(&self, item: PyObject) -> PyResult<bool> {

```