Fix tox integration test.

- Missing a requirement of fake_mysos_executor.
- Should use os.setpgrp() for task subprocess.
diff --git a/mysos/executor/testing/fake.py b/mysos/executor/testing/fake.py
index c479289..c203eb3 100644
--- a/mysos/executor/testing/fake.py
+++ b/mysos/executor/testing/fake.py
@@ -52,7 +52,7 @@
     if self._process:
       return
 
-    self._process = subprocess.Popen(self._mysqld, shell=True, preexec_fn=os.setsid)
+    self._process = subprocess.Popen(self._mysqld, shell=True, preexec_fn=os.setpgrp)
     subprocess.check_call(self._start_cmd, shell=True)
     return self._process
 
diff --git a/tox.ini b/tox.ini
index 7d4fd2d..95cad9f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -19,6 +19,7 @@
     --source-dir={toxinidir} \
     --output-file={toxinidir}/dist/fake_mysos_executor.pex \
     --requirement=mesos.native \
+    --requirement=zake \
     --repo={toxinidir}/3rdparty \
     --entry-point="mysos.executor.testing.fake_mysos_executor:proxy_main"
   py.test -v -k 'test_scheduler_runs' tests {posargs:}