io_jail: correct io_jail tests that used Minijail::enter()

This also updates the `build_test.py` to use the command line option to
run certain certain test modules serially.

TEST=./build_test
BUG=None

Change-Id: I8a498514cb6b89fab01f02d0ef8faf39629f717c
Reviewed-on: https://chromium-review.googlesource.com/748824
Commit-Ready: Zach Reizner <zachr@chromium.org>
Tested-by: Zach Reizner <zachr@chromium.org>
Reviewed-by: Dylan Reid <dgreid@chromium.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/build_test.py b/build_test.py
index 243e115..2dfefe4 100755
--- a/build_test.py
+++ b/build_test.py
@@ -97,14 +97,14 @@ def test_target_modules(triple, is_release, env, modules, parallel):
   if is_release:
     args.append('--release')
 
-  if not parallel:
-    env = env.copy()
-    env['RUST_TEST_THREADS'] = '1'
-
   for mod in modules:
     args.append('-p')
     args.append(mod)
 
+  if not parallel:
+    args.append('--')
+    args.append('--test-threads=1')
+
   return subprocess.Popen(args, env=env).wait() == 0