sim_vehicle.py: simply ignore any failure to kill tasks

Tools/autotest/sim_vehicle.py

@@ -106,7 +106,6 @@ def kill_tasks_psutil(victims):
 
 def kill_tasks_pkill(victims):
     '''shell out to pkill(1) to kill processed by name'''
-    progress("Killing tasks")
     for victim in victims: # pkill takes a single pattern, so iterate
         cmd = ["pkill"]
         cmd.append(victim)
@@ -117,6 +116,8 @@ class BobException(Exception):
 
 def kill_tasks():
     '''clean up stray processes by name.  This is a somewhat shotgun approach'''
+    progress("Killing tasks")
+    try:
         victim_names = [
             'JSBSim',
             'lt-JSBSim',
@@ -137,6 +138,8 @@ def kill_tasks():
             kill_tasks_psutil(victim_names)
         except ImportError as e:
             kill_tasks_pkill(victim_names)
+    except Exception as e:
+        progress("kill_tasks failed: {}".format(str(e)))
 
 # clean up processes at exit:
 atexit.register(kill_tasks)