Fix handling of `sys.base_prefix` collision in interpreter identity check during tool installs (#7596)

Closes https://github.com/astral-sh/uv/issues/7586

Extends https://github.com/astral-sh/uv/pull/7593 (thanks @lucab!)

---------

Co-authored-by: Luca BRUNO <lucab@lucabruno.net>

Cargo.lock

@@ -4482,6 +4482,7 @@ dependencies = [
  "regex",
  "reqwest",
  "rustc-hash",
+ "same-file",
  "serde",
  "serde_json",
  "similar",

crates/uv/Cargo.toml

@@ -66,6 +66,7 @@ owo-colors = { workspace = true }
 rayon = { workspace = true }
 regex = { workspace = true }
 rustc-hash = { workspace = true }
+same-file = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 tempfile = { workspace = true }

crates/uv/src/commands/tool/install.rs

@@ -276,13 +276,23 @@ pub(crate) async fn install(
         installed_tools
             .get_environment(&from.name, &cache)?
             .filter(|environment| {
-                // NOTE(lucab): this compares `base_prefix` paths as a proxy for
+                // TODO(zanieb): Consider using `sysconfig.get_path("stdlib")` instead, which
-                // detecting interpreters mismatches. Directly comparing interpreters
+                // should be generally robust.
-                // (by paths or binaries on-disk) would result in several false
+                // TODO(zanieb): Move this into a utility on `Interpreter` since it's non-trivial.
-                // positives on Windows due to file-copying and shims.
+                let same_interpreter = if cfg!(windows) {
+                    // On Windows, we can't canonicalize an interpreter based on its executable path
+                    // because the executables are separate shim files (not links). Instead, we
+                    // compare the `sys.base_prefix`.
                     let old_base_prefix = environment.interpreter().sys_base_prefix();
                     let selected_base_prefix = interpreter.sys_base_prefix();
-                if old_base_prefix == selected_base_prefix {
+                    old_base_prefix == selected_base_prefix
+                } else {
+                    // On Unix, we can see if the canonicalized executable is the same file.
+                    environment.interpreter().sys_executable() == interpreter.sys_executable()
+                        || same_file::is_same_file(environment.interpreter().sys_executable(), interpreter.sys_executable()).unwrap_or(false)
+                };
+
+                if same_interpreter {
                     trace!(
                         "Existing interpreter matches the requested interpreter for `{}`: {}",
                         from.name,