"roslaunch explore_stage explore.launch" problem

edit

plz heeelllpp! :( i used explore_stage before, but after upgrade my ubuntu, it gave me this error!

mohsen@mohsen-ThinkPad-R500:~$ roslaunch explore_stage explore.launch
... logging to /home/mohsen/.ros/log/e3e2f4c6-bca0-11e2-b4c1-001c259b7f6b/roslaunch-mohsen-ThinkPad-R500-5445.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

WARNING: ignoring defunct <master /> tag
started roslaunch server http://mohsen-ThinkPad-R500:43843/

SUMMARY
========

PARAMETERS
 * /explore/close_loops
 * /explore/explore_costmap/base_scan/clearing
 * /explore/explore_costmap/base_scan/data_type
 * /explore/explore_costmap/base_scan/expected_update_rate
 * /explore/explore_costmap/base_scan/marking
 * /explore/explore_costmap/base_scan/observation_persistance
 * /explore/explore_costmap/base_scan/sensor_frame
 * /explore/explore_costmap/circumscribed_radius
 * /explore/explore_costmap/cost_scaling_factor
 * /explore/explore_costmap/global_frame
 * /explore/explore_costmap/height
 * /explore/explore_costmap/inflation_radius
 * /explore/explore_costmap/inscribed_radius
 * /explore/explore_costmap/lethal_cost_threshold
 * /explore/explore_costmap/map_type
 * /explore/explore_costmap/max_obstacle_height
 * /explore/explore_costmap/observation_sources
 * /explore/explore_costmap/obstacle_range
 * /explore/explore_costmap/origin_x
 * /explore/explore_costmap/origin_y
 * /explore/explore_costmap/publish_frequency
 * /explore/explore_costmap/raytrace_range
 * /explore/explore_costmap/resolution
 * /explore/explore_costmap/robot_base_frame
 * /explore/explore_costmap/rolling_window
 * /explore/explore_costmap/static_map
 * /explore/explore_costmap/track_unknown_space
 * /explore/explore_costmap/transform_tolerance
 * /explore/explore_costmap/update_frequency
 * /explore/explore_costmap/width
 * /explore/gain_scale
 * /explore/orientation_scale
 * /explore/potential_scale
 * /move_base/NavfnROS/transform_tolerance
 * /move_base/TrajectoryPlannerROS/acc_lim_th
 * /move_base/TrajectoryPlannerROS/acc_lim_x
 * /move_base/TrajectoryPlannerROS/acc_lim_y
 * /move_base/TrajectoryPlannerROS/dwa
 * /move_base/TrajectoryPlannerROS/escape_reset_dist
 * /move_base/TrajectoryPlannerROS/escape_reset_theta
 * /move_base/TrajectoryPlannerROS/goal_distance_bias
 * /move_base/TrajectoryPlannerROS/heading_lookahead
 * /move_base/TrajectoryPlannerROS/heading_scoring
 * /move_base/TrajectoryPlannerROS/heading_scoring_timestep
 * /move_base/TrajectoryPlannerROS/holonomic_robot
 * /move_base/TrajectoryPlannerROS/max_vel_th
 * /move_base/TrajectoryPlannerROS/max_vel_x
 * /move_base/TrajectoryPlannerROS/min_in_place_vel_th
 * /move_base/TrajectoryPlannerROS/min_vel_th
 * /move_base/TrajectoryPlannerROS/min_vel_x
 * /move_base/TrajectoryPlannerROS/occdist_scale
 * /move_base/TrajectoryPlannerROS/oscillation_reset_dist
 * /move_base/TrajectoryPlannerROS/path_distance_bias
 * /move_base/TrajectoryPlannerROS/sim_granularity
 * /move_base/TrajectoryPlannerROS/sim_time
 * /move_base/TrajectoryPlannerROS/simple_attractor
 * /move_base/TrajectoryPlannerROS/transform_tolerance
 * /move_base/TrajectoryPlannerROS/vtheta_samples
 * /move_base/TrajectoryPlannerROS/vx_samples
 * /move_base/TrajectoryPlannerROS/world_model
 * /move_base/TrajectoryPlannerROS/xy_goal_tolerance
 * /move_base/TrajectoryPlannerROS/yaw_goal_tolerance
 * /move_base/footprint
 * /move_base/global_costmap/base_scan/clearing
 * /move_base/global_costmap/base_scan/data_type
 * /move_base/global_costmap/base_scan/expected_update_rate
 * /move_base/global_costmap/base_scan/marking
 * /move_base/global_costmap/base_scan/observation_persistance
 * /move_base/global_costmap/base_scan/sensor_frame
 * /move_base/global_costmap/circumscribed_radius
 * /move_base/global_costmap/cost_scaling_factor
 * /move_base/global_costmap/global_frame
 * /move_base/global_costmap/height
 * /move_base/global_costmap/inflation_radius
 * /move_base/global_costmap/inscribed_radius
 * /move_base/global_costmap/lethal_cost_threshold
 * /move_base/global_costmap/map_type
 * /move_base/global_costmap/max_obstacle_height
 * /move_base/global_costmap/observation_sources
 * /move_base/global_costmap/obstacle_range
 * /move_base/global_costmap/origin_x
 * /move_base/global_costmap/origin_y
 * /move_base/global_costmap/publish_frequency
 * /move_base/global_costmap/raytrace_range
 * /move_base/global_costmap/resolution
 * /move_base/global_costmap/robot_base_frame
 * /move_base/global_costmap/rolling_window
 * /move_base/global_costmap/static_map
 * /move_base/global_costmap/transform_tolerance
 * /move_base/global_costmap/update_frequency
 * /move_base/global_costmap/width
 * /move_base/local_costmap/base_scan/clearing
 * /move_base/local_costmap/base_scan/data_type
 * /move_base/local_costmap/base_scan/expected_update_rate
 * /move_base/local_costmap/base_scan/marking
 * /move_base/local_costmap/base_scan/observation_persistance
 * /move_base/local_costmap/base_scan/sensor_frame
 * /move_base/local_costmap/circumscribed_radius
 * /move_base/local_costmap/cost_scaling_factor
 * /move_base/local_costmap/global_frame
 * /move_base/local_costmap/height
 * /move_base/local_costmap/inflation_radius
 * /move_base/local_costmap/inscribed_radius
 * /move_base/local_costmap/lethal_cost_threshold
 * /move_base/local_costmap/map_type
 * /move_base/local_costmap/max_obstacle_height
 * /move_base/local_costmap/observation_sources
 * /move_base/local_costmap/obstacle_range
 * /move_base/local_costmap/origin_x
 * /move_base/local_costmap/origin_y
 * /move_base/local_costmap/publish_frequency
 * /move_base/local_costmap/raytrace_range
 * /move_base/local_costmap/resolution
 * /move_base/local_costmap/robot_base_frame
 * /move_base/local_costmap/rolling_window
 * /move_base/local_costmap/static_map
 * /move_base/local_costmap/transform_tolerance
 * /move_base/local_costmap/update_frequency
 * /move_base/local_costmap/width
 * /rosdistro
 * /rosversion
 * /use_sim_time

NODES
  /
    explore (explore/explore)
    fake_localize (tf/static_transform_publisher)
    move_base (move_base/move_base)
    stage (stage/stageros)

auto-starting new master
Exception AttributeError: AttributeError("'_DummyThread' object has no attribute '_Thread__block'",) in <module 'threading' from '/usr/lib/python2.7/threading.pyc'> ignored
process[master]: started with pid [5461]
ROS_MASTER_URI=http://localhost:11311

setting /run_id to e3e2f4c6-bca0-11e2-b4c1-001c259b7f6b
Exception AttributeError: AttributeError("'_DummyThread' object has no attribute '_Thread__block'",) in ...