diff -r 6380efb82191 -r 5893706af3de rust/hg-cpython/src/revlog.rs
--- a/rust/hg-cpython/src/revlog.rs	Mon Jan 25 12:00:23 2021 +0100
+++ b/rust/hg-cpython/src/revlog.rs	Mon Jan 25 12:28:39 2021 +0100
@@ -18,7 +18,7 @@
 use hg::{
     nodemap::{Block, NodeMapError, NodeTree},
     revlog::{nodemap::NodeMap, RevlogIndex},
-    NodeError, Revision,
+    Revision,
 };
 use std::cell::RefCell;
 
@@ -468,17 +468,12 @@
     match err {
         NodeMapError::MultipleResults => revlog_error(py),
         NodeMapError::RevisionNotInIndex(r) => rev_not_in_index(py, r),
-        NodeMapError::InvalidNodePrefix(s) => invalid_node_prefix(py, &s),
+        NodeMapError::InvalidNodePrefix => {
+            PyErr::new::<ValueError, _>(py, "Invalid node or prefix")
+        }
     }
 }
 
-fn invalid_node_prefix(py: Python, ne: &NodeError) -> PyErr {
-    PyErr::new::<ValueError, _>(
-        py,
-        format!("Invalid node or prefix: {:?}", ne),
-    )
-}
-
 /// Create the module, with __package__ given from parent
 pub fn init_module(py: Python, package: &str) -> PyResult<PyModule> {
     let dotted_name = &format!("{}.revlog", package);