fix fs bug on CI

Signed-off-by: onur-ozkan <[email protected]>

Author: onur-ozkan

src/bootstrap/src/core/build_steps/compile.rs

@@ -789,6 +789,14 @@ impl Step for StdLink {
             }
         } else if compiler.stage == 0 {
             let sysroot = builder.out.join(compiler.host.triple).join("stage0-sysroot");
+
+            if builder.local_rebuild {
+                // On local rebuilds this path might be a symlink to the project root,
+                // which can be read-only (e.g., on CI). So remove it before copying
+                // the stage0 lib.
+                let _ = fs::remove_dir_all(sysroot.join("lib/rustlib/src/rust"));
+            }
+
             builder.cp_link_r(&builder.initial_sysroot.join("lib"), &sysroot.join("lib"));
         } else {
             if builder.download_rustc() {