remove unnecessary git usages

`Config::src` already contains the top-level path, so we don't need to
add git overhead just to reach this path.
Signed-off-by: onur-ozkan <work@onurozkan.dev>

Author: onur-ozkan

src/bootstrap/src/core/config/config.rs

@@ -2445,14 +2445,6 @@ impl Config {
 }
 };
 
-// Handle running from a directory other than the top level
-let top_level = output(
-&mut helpers::git(Some(&self.src)).args(["rev-parse","--show-toplevel"]).command,
-);
-let top_level = top_level.trim_end();
-let compiler = format!("{top_level}/compiler/");
-let library = format!("{top_level}/library/");
-
 // Look for a version to compare to based on the current commit.
 // Only commits merged by bors will have CI artifacts.
 let merge_base = output(
@@ -2473,7 +2465,9 @@ impl Config {
 
 // Warn if there were changes to the compiler or standard library since the ancestor commit.
 let has_changes = !t!(helpers::git(Some(&self.src))
-.args(["diff-index","--quiet", commit,"--",&compiler,&library])
+.args(["diff-index","--quiet", commit])
+.arg("--")
+.args([self.src.join("compiler"),self.src.join("library")])
 .command
 .status())
 .success();
@@ -2545,12 +2539,6 @@ impl Config {
 option_name:&str,
 if_unchanged:bool,
 ) -> Option<String>{
-// Handle running from a directory other than the top level
-let top_level = output(
-&mut helpers::git(Some(&self.src)).args(["rev-parse","--show-toplevel"]).command,
-);
-let top_level = top_level.trim_end();
-
 // Look for a version to compare to based on the current commit.
 // Only commits merged by bors will have CI artifacts.
 let merge_base = output(
@@ -2573,8 +2561,11 @@ impl Config {
 letmut git = helpers::git(Some(&self.src));
  git.args(["diff-index","--quiet", commit,"--"]);
 
+// Handle running from a directory other than the top level
+let top_level = &self.src;
+
 for path in modified_paths {
- git.arg(format!("{top_level}/{path}"));
+ git.arg(top_level.join(path));
 }
 
 let has_changes = !t!(git.command.status()).success();