Cache which git in uv init (#12893)

Avoid running `which` multiple times, to be more coherent with the other
git code. In preparation of improving the `uv init` git handling.

Cargo.lock

@@ -4955,12 +4955,12 @@ dependencies = [
  "uv-cache-info",
  "uv-cache-key",
  "uv-distribution-types",
+ "uv-git",
  "uv-normalize",
  "uv-pep440",
  "uv-pep508",
  "uv-platform-tags",
  "uv-static",
- "which",
 ]
 
 [[package]]

crates/uv-configuration/Cargo.toml

@@ -21,6 +21,7 @@ uv-cache = { workspace = true }
 uv-cache-info = { workspace = true }
 uv-cache-key = { workspace = true }
 uv-distribution-types = { workspace = true }
+uv-git = { workspace = true }
 uv-normalize = { workspace = true }
 uv-pep440 = { workspace = true }
 uv-pep508 = { workspace = true, features = ["schemars"] }
@@ -40,7 +41,6 @@ serde_json = { workspace = true }
 thiserror = { workspace = true }
 tracing = { workspace = true }
 url = { workspace = true }
-which = { workspace = true }
 
 [dev-dependencies]
 anyhow = { workspace = true }

crates/uv-configuration/src/vcs.rs

@@ -4,6 +4,7 @@ use std::process::{Command, Stdio};
 
 use serde::Deserialize;
 use tracing::debug;
+use uv_git::GIT;
 
 #[derive(Debug, thiserror::Error)]
 pub enum VersionControlError {
@@ -35,7 +36,7 @@ impl VersionControlSystem {
     pub fn init(&self, path: &Path) -> Result<(), VersionControlError> {
         match self {
             Self::Git => {
-                let Ok(git) = which::which("git") else {
+                let Ok(git) = GIT.as_ref() else {
                     return Err(VersionControlError::GitNotInstalled);
                 };
 
@@ -80,17 +81,16 @@ impl VersionControlSystem {
     /// Detects the VCS system based on the provided path.
     pub fn detect(path: &Path) -> Option<Self> {
         // Determine whether the path is inside a Git work tree.
-        if which::which("git").is_ok_and(|git| {
-            Command::new(git)
-                .arg("rev-parse")
-                .arg("--is-inside-work-tree")
-                .current_dir(path)
-                .stdout(Stdio::null())
-                .stderr(Stdio::null())
-                .status()
-                .map(|status| status.success())
-                .unwrap_or(false)
-        }) {
+        let git = GIT.as_ref().ok()?;
+        let exit_status = Command::new(git)
+            .arg("rev-parse")
+            .arg("--is-inside-work-tree")
+            .current_dir(path)
+            .stdout(Stdio::null())
+            .stderr(Stdio::null())
+            .status()
+            .ok()?;
+        if exit_status.success() {
             return Some(Self::Git);
         }