Detach engine popen process with parent process

blimp/tools/client_engine_integration.py

Index: blimp/tools/client_engine_integration.py
diff --git a/blimp/tools/client_engine_integration.py b/blimp/tools/client_engine_integration.py
index 3f45e3fb8a5dae93ffc23f3c3dfd8426b319493d..6918ae289c5528dd7a6f654c49442a213e12c5e8 100755
--- a/blimp/tools/client_engine_integration.py
+++ b/blimp/tools/client_engine_integration.py
@@ -105,7 +105,8 @@ def RunEngine(output_linux_directory, token_file_path, device):
       ' --vmodule="blimp*=1"']
   p = subprocess.Popen(run_engine_cmd, shell=True,
                        stdout=subprocess.PIPE,
-                       stderr=subprocess.STDOUT)
+                       stderr=subprocess.STDOUT,
+                       preexec_fn=os.setsid)

[shenghuazhang, 2016/08/26 19:47:41]

This shall creates a new process for the popen. Not sure if this could avoid
recipe waiting though.
Couldn't I check it unless commit it into the bot?
'scripts/slave/unittests/recipe_simulation_test.py train' won't verify this I
think.

[jbudorick, 2016/08/26 21:15:06]

No, the simulation test won't verify this. Testing it on an fyi bot is probably
the best way to see if it works.

 
   for line in iter(p.stdout.readline, ''):
     sys.stdout.write(line)