xend: On block-attach, remove device information when VmError occurs.

I tested xm block-attach command with a wrong
parameter(file:). Naturally a command error occurred. Then I retested
xm block-attach command with a correct parameter(phy:). But a command
error occurred again. The second command error occurred because Xend
did not remove device information from self.info when the first
command error occurred.

Signed-off-by: Masaki Kanno <kanno.masaki@jp.fujitsu.com>

tools/python/xen/xend/XendDomainInfo.py

@@ -535,6 +535,11 @@ class XendDomainInfo:
                     self._createDevice(dev_type, dev_config_dict)
                 self._waitForDevice(dev_type, devid)
             except VmError, ex:
+                del self.info['devices'][dev_uuid]
+                if dev_type == 'tap':
+                    self.info['vbd_refs'].remove(dev_uuid)
+                else:
+                    self.info['%s_refs' % dev_type].remove(dev_uuid)
                 raise ex
         else:
             devid = None