Integration tests: make sure qemu exits in fixture finalizer

Also, make sure qemu is alive in wait_for_ssh.

tests/integration/rostest/test_00_system.py

@@ -1,7 +1,8 @@
 from __future__ import print_function
-import itertools as it
-import pytest
+
 import subprocess
+
+import pytest
 import rostest.util as u
 
 
@@ -14,21 +15,12 @@ def qemu(request):
 def test_system_boot(qemu):
     version = u.rancheros_version('./build.conf')
     print('parsed version: ' + version)
-
-    def has_ros_started_substr(s):
-        return str.find(s, 'RancherOS {v} started'.format(v=version)) > -1
-
-    for _ in it.ifilter(has_ros_started_substr,
-                        it.imap(u.with_effect(print), u.iter_lines(qemu.stdout))):
-        assert True
-        return
-    assert False
+    u.flush_out(qemu.stdout, 'RancherOS {v} started'.format(v=version))
 
 
 @pytest.mark.timeout(60)
 def test_run_system_container(qemu):
-    assert qemu is not None
-    u.wait_for_ssh()
+    u.wait_for_ssh(qemu)
 
     ssh = subprocess.Popen(
         './scripts/ssh --qemu sudo system-docker run --rm busybox /bin/true',