More resilient registry removal (#14717)

With the previous order of operations, there could be warnings from race
conditions between two process A and B removing and installing Python
versions.

* A removes the files for CPython3.9.18
* B sees the key CPython3.9.18
* B sees that CPython3.9.18 has no files
* A removes the key for CPython3.9.18
* B try to removes the key for CPython3.9.18, gets and error that it's
already gone, issues a warning

We make the more resilient in two ways:

* We remove the registry key first, avoiding dangling registry keys in
the removal process
* We ignore not found errors in registry removal operations: If we try
to remove something that's already gone, that's fine.

Fixes #14714 (hopefully)

crates/uv-python/src/windows_registry.rs

@@ -268,6 +268,9 @@ pub fn remove_orphan_registry_entries(installations: &[ManagedPythonInstallation
     // Separate assignment since `keys()` creates a borrow.
     let subkeys = match key.keys() {
         Ok(subkeys) => subkeys,
+        Err(err) if err.code() == ERROR_NOT_FOUND => {
+            return;
+        }
         Err(err) => {
             // TODO(konsti): We don't have an installation key here.
             warn_user_once!("Failed to list subkeys of HKCU:\\{astral_key}: {err}");
@@ -281,6 +284,9 @@ pub fn remove_orphan_registry_entries(installations: &[ManagedPythonInstallation
         let python_entry = format!("{astral_key}\\{subkey}");
         debug!("Removing orphan registry key HKCU:\\{}", python_entry);
         if let Err(err) = CURRENT_USER.remove_tree(&python_entry) {
+            if err.code() == ERROR_NOT_FOUND {
+                continue;
+            }
             // TODO(konsti): We don't have an installation key here.
             warn_user_once!("Failed to remove orphan registry key HKCU:\\{python_entry}: {err}");
         }

crates/uv/src/commands/python/uninstall.rs

@@ -142,6 +142,19 @@ async fn do_uninstall(
         return Ok(ExitStatus::Failure);
     }
 
+    // Remove registry entries first, so we don't have dangling entries between the file removal
+    // and the registry removal.
+    let mut errors = vec![];
+    #[cfg(windows)]
+    {
+        uv_python::windows_registry::remove_registry_entry(
+            &matching_installations,
+            all,
+            &mut errors,
+        );
+        uv_python::windows_registry::remove_orphan_registry_entries(&installed_installations);
+    }
+
     // Find and remove all relevant Python executables
     let mut uninstalled_executables: FxHashMap<PythonInstallationKey, FxHashSet<PathBuf>> =
         FxHashMap::default();
@@ -201,7 +214,6 @@ async fn do_uninstall(
     }
 
     let mut uninstalled = IndexSet::<PythonInstallationKey>::default();
-    let mut errors = vec![];
     while let Some((key, result)) = tasks.next().await {
         if let Err(err) = result {
             errors.push((key.clone(), anyhow::Error::new(err)));
@@ -210,16 +222,6 @@ async fn do_uninstall(
         }
     }
 
-    #[cfg(windows)]
-    {
-        uv_python::windows_registry::remove_registry_entry(
-            &matching_installations,
-            all,
-            &mut errors,
-        );
-        uv_python::windows_registry::remove_orphan_registry_entries(&installed_installations);
-    }
-
     // Read all existing managed installations and find the highest installed patch
     // for each installed minor version. Ensure the minor version link directory
     // is still valid.