From b436dca9e6d9bb47c9f63b7269c19392c60833d0 Mon Sep 17 00:00:00 2001
From: Mark Simulacrum <mark.simulacrum@gmail.com>
Date: Sat, 16 Jun 2018 11:12:15 -0600
Subject: [PATCH] Prevent Windows filesystem races in bootstrap tests

---
 src/bootstrap/test.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index a0b6222421d71..ce6506b0a10fa 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -1921,6 +1921,9 @@ impl Step for Bootstrap {
             cmd.arg("--no-fail-fast");
         }
         cmd.arg("--").args(&builder.config.cmd.test_args());
+        // rustbuild tests are racy on directory creation so just run them one at a time.
+        // Since there's not many this shouldn't be a problem.
+        cmd.arg("--test-threads=1");
         try_run(builder, &mut cmd);
     }