Improve log when distutils is missing (#10713)

See https://github.com/astral-sh/uv/issues/4204 for motivation

This doesn't really reach the user experience I'd expect — i.e., we end
up saying a virtual environment "does not exist" which is a little
silly. However, I think improving the error messaging on interpreter
queries in general should be solved separately. I did one small
"general" change in
https://github.com/astral-sh/uv/pull/10713/commits/89e11d022222a999a4ba8eb73397ea314a636811
— otherwise we don't show the message at all.

---------

Co-authored-by: konsti <konstin@mailbox.org>

crates/uv-python/src/discovery.rs

@@ -720,8 +720,7 @@ impl Error {
                 InterpreterError::Encode(_)
                 | InterpreterError::Io(_)
                 | InterpreterError::SpawnFailed { .. } => true,
-                InterpreterError::QueryScript { path, .. }
-                | InterpreterError::UnexpectedResponse { path, .. }
+                InterpreterError::UnexpectedResponse { path, .. }
                 | InterpreterError::StatusCode { path, .. } => {
                     debug!(
                         "Skipping bad interpreter at {} from {source}: {err}",
@@ -729,6 +728,13 @@ impl Error {
                     );
                     false
                 }
+                InterpreterError::QueryScript { path, err } => {
+                    debug!(
+                        "Skipping bad interpreter at {} from {source}: {err}",
+                        path.display()
+                    );
+                    false
+                }
                 InterpreterError::NotFound(path) => {
                     // If the interpreter is from an active, valid virtual environment, we should
                     // fail because it's broken

crates/uv-python/src/interpreter.rs

@@ -604,6 +604,11 @@ pub enum InterpreterInfoError {
     UnsupportedPythonVersion { python_version: String },
     #[error("Python executable does not support `-I` flag. Please use Python 3.8 or newer.")]
     UnsupportedPython,
+    #[error("Python installation is missing `distutils`, which is required for packaging on older Python versions. Your system may package it separately, e.g., as `python{python_major}-distutils` or `python{python_major}.{python_minor}-distutils`.")]
+    MissingRequiredDistutils {
+        python_major: usize,
+        python_minor: usize,
+    },
 }
 
 #[derive(Debug, Deserialize, Serialize, Clone)]