xend hvm: Fix 'monitor=1' handling in domain config file.

Fix wrong python list assignment for "monitor=1". The old assignment
only works when using qemu-dm.debug in configure file.

Signed-off-by: You YongKang <yongkang.you@intel.com>
Signed-off-by: Zhang Xin <xing.z.zhang@intel.com>

tools/python/xen/xend/image.py

@@ -418,7 +418,7 @@ class HVMImageHandler(ImageHandler):
             ret.append('-nographic')
 
         if int(vmConfig['platform'].get('monitor', 0)) != 0:
-            ret.append('-monitor vc')
+            ret = ret + ['-monitor', 'vc']
         return ret
 
     def createDeviceModel(self, restore = False):