[autoroll] make autoroller propagate changes to recipes.py.

unittests/autoroll_test.py

Index: unittests/autoroll_test.py
diff --git a/unittests/autoroll_test.py b/unittests/autoroll_test.py
index 9c7d8246956291b4513c7e14bf5b43af6dc25857..c1168f4a0f43fe5e52228d2323093bf40a0fb24e 100755
--- a/unittests/autoroll_test.py
+++ b/unittests/autoroll_test.py
@@ -19,16 +19,20 @@ class TestAutoroll(repo_test_util.RepoTest):
     """
     with repo_test_util.in_directory(repo['root']), \
         repo_test_util.temporary_file() as tempfile_path:
-      subprocess.check_output([
+      try:
+        subprocess.check_output([
           sys.executable, self._recipe_tool,
           '--package', os.path.join(
-              repo['root'], 'infra', 'config', 'recipes.cfg'),
+            repo['root'], 'infra', 'config', 'recipes.cfg'),
           '--use-bootstrap',
           'autoroll',
           '--output-json', tempfile_path
-      ] + list(args), stderr=subprocess.STDOUT)
-      with open(tempfile_path) as f:
-        return json.load(f)
+        ] + list(args) , stderr=subprocess.STDOUT)
+        with open(tempfile_path) as f:
+          return json.load(f)
+      except subprocess.CalledProcessError as e:
+        print e.output
+        raise
 
   def test_empty(self):
     """Tests the scenario where there are no roll candidates.