debugindexstats: handle the lack of Rust support better

We don't have any stats in the Rust index. Currently it is not known which
stats would be interesting to get, so if they end up being important, we can
add them later.

mercurial/debugcommands.py

@@ -1860,7 +1860,7 b' def debugindexstats(ui, repo):'
     repo.changelog.shortest(repo.nullid, 1)
     index = repo.changelog.index
     if not hasattr(index, 'stats'):
-        raise error.Abort(_(b'debugindexstats only works with native code'))
+        raise error.Abort(_(b'debugindexstats only works with native C code'))
     for k, v in sorted(index.stats().items()):
         ui.write(b'%s: %d\n' % (k, v))
 

rust/hg-cpython/src/revlog.rs

@@ -405,11 +405,6 b' py_class!(pub class MixedIndex |py| {'
         Ok(rust_res)
     }
 
-    /// stats for the index
-    def stats(&self, *args, **kw) -> PyResult<PyObject> {
-        self.call_cindex(py, "stats", args, kw)
-    }
-
     // index_sequence_methods and index_mapping_methods.
     //
     // Since we call back through the high level Python API,

tests/test-debugcommands.t

@@ -185,12 +185,12 b' Test debugindex, with and without the --'
 
 debugdelta chain basic output
 
-#if reporevlogstore pure
+#if reporevlogstore pure rust
   $ hg debugindexstats
-  abort: debugindexstats only works with native code
+  abort: debugindexstats only works with native C code
   [255]
 #endif
-#if reporevlogstore no-pure
+#if reporevlogstore no-pure no-rust
   $ hg debugindexstats
   node trie capacity: 4
   node trie count: 2