monitor: run promise script should not fail when json is bad

stack/monitor/buildout.cfg

@@ -137,7 +137,7 @@ md5sum = 280412f9024030c8cae343c2b07e5130
 recipe = slapos.recipe.template:jinja2
 template = ${:_profile_base_location_}/scripts/run-promise.py
 rendered = ${buildout:parts-directory}/monitor-scripts/run-promise.py
-md5sum = 2570b11cd1f718f240a9c7a05ffa861d
+md5sum = 641c6917bbd19a7abaebb120ccd4e713
 mode = 0755
 context =
   raw python ${buildout:directory}/bin/${extra-eggs:interpreter}

stack/monitor/scripts/run-promise.py

@@ -10,6 +10,7 @@ import time
 from shutil import copyfile
 import glob
 import argparse
+import traceback
 
 def parseArguments():
   """
@@ -71,9 +72,12 @@ def main():
   status_json['change-time'] = ps_process.create_time()
   if os.path.exists(parser.output):
     with open(parser.output) as f:
+      try:
         last_result = json.loads(f.read())
         if status_json['status'] == last_result['status'] and last_result.has_key('change-time'):
           status_json['change-time'] = last_result['change-time']
+      except ValueError:
+        pass
 
   updateStatusHistoryFolder(
     parser.promise_name,
@@ -99,7 +103,11 @@ def updateStatusHistoryFolder(name, status_file, history_folder, promise_type):
         pass
       else: raise
   with open(status_file, 'r') as sf:
+    try:
       status_dict = json.loads(sf.read())
+    except ValueError:
+      traceback.print_exc()
+      return
 
   if promise_type == 'status':
     filename = '%s.history.json' % name