Use subprocess42 in recipe_engine to avoid threading madness.

recipe_engine/unittests/run_test.py

Index: recipe_engine/unittests/run_test.py
diff --git a/recipe_engine/unittests/run_test.py b/recipe_engine/unittests/run_test.py
index da6b81c15c163f500fed04959cb2a9e1417f6a4e..06ead3fe0c2cbfbb9b70c33fbad7ba82771cbd27 100755
--- a/recipe_engine/unittests/run_test.py
+++ b/recipe_engine/unittests/run_test.py
@@ -9,6 +9,7 @@ import re
 import subprocess
 import sys
 import unittest
+import time
 
 BASE_DIR = os.path.dirname(os.path.dirname(os.path.dirname(
                            os.path.abspath(__file__))))
@@ -143,7 +144,7 @@ class RunTest(unittest.TestCase):
         self._run_cmd('engine_tests/subannotations'),
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE)
-    stdout, stderr = proc.communicate()
+    stdout, _ = proc.communicate()
     self.assertRegexpMatches(stdout, r'(?m)^!@@@BUILD_STEP@steppy@@@$')
     self.assertRegexpMatches(stdout, r'(?m)^@@@BUILD_STEP@pippy@@@$')
     # Before 'Subannotate me' we expect an extra STEP_CURSOR to reset the
@@ -151,6 +152,16 @@ class RunTest(unittest.TestCase):
     self.assertRegexpMatches(stdout,
         r'(?m)^@@@STEP_CURSOR@Subannotate me@@@\n@@@STEP_CLOSED@@@$')
 
+  def test_bad_subprocess(self):
+    now = time.time()
+    self._test_recipe('engine_tests/bad_subprocess')
+    after = time.time()
+
+    # Test has an internal 10s timeout for the bad daemon step, but the daemon's
+    # parent process quits immediately. If this takes longer than 5 seconds to
+    # run, we consider it failed.
+    self.assertLess(after - now, 5)
+
 
 if __name__ == '__main__':
   unittest.TestCase.maxDiff = None