If a test has issued a quit command already (which may be useful to do
explicitly because the test wants to show its effects),
QEMUMachine.shutdown() should not do so again.  Otherwise, the VM may
well return an ECONNRESET which will lead QEMUMachine.shutdown() to
killing it, which then turns into a "qemu received signal 9" line.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 python/qemu/__init__.py | 5 +++--
 tests/qemu-iotests/255  | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/python/qemu/__init__.py b/python/qemu/__init__.py
index dbaf8a5311..25207a2970 100644
--- a/python/qemu/__init__.py
+++ b/python/qemu/__init__.py
@@ -332,13 +332,14 @@ class QEMUMachine(object):
         self._load_io_log()
         self._post_shutdown()
 
-    def shutdown(self):
+    def shutdown(self, has_quit=False):
         """
         Terminate the VM and clean up
         """
         if self.is_running():
             try:
-                self._qmp.cmd('quit')
+                if not has_quit:
+                    self._qmp.cmd('quit')
                 self._qmp.close()
             except:
                 self._popen.kill()
diff --git a/tests/qemu-iotests/255 b/tests/qemu-iotests/255
index 49433ec122..3632d507d0 100755
--- a/tests/qemu-iotests/255
+++ b/tests/qemu-iotests/255
@@ -132,4 +132,4 @@ with iotests.FilePath('src.qcow2') as src_path, \
     vm.qmp_log('block-job-cancel', device='job0')
     vm.qmp_log('quit')
 
-    vm.shutdown()
+    vm.shutdown(has_quit=True)
-- 
2.21.0