--- a/rust/hg-pyo3/src/exceptions.rs	Wed Dec 25 17:17:47 2024 +0100
+++ b/rust/hg-pyo3/src/exceptions.rs	Tue Dec 24 15:08:22 2024 +0100
@@ -3,6 +3,7 @@
 use pyo3::{create_exception, PyErr};
 
 use hg::revlog::nodemap::NodeMapError;
+use hg::UncheckedRevision;
 
 use crate::revision::PyRevision;
 
@@ -58,6 +59,11 @@
     mercurial_py_errors::RevlogError::new_err((None::<String>,))
 }
 
+#[allow(dead_code)]
+pub fn rev_not_in_index(rev: UncheckedRevision) -> PyErr {
+    PyValueError::new_err(format!("revlog index out of range: {}", rev))
+}
+
 pub fn nodemap_error(err: NodeMapError) -> PyErr {
     match err {
         NodeMapError::MultipleResults => {