message: Fix crash in redex.py when supplying a value for a key that's not in the config
  Summary:
  If you run redex.py with -J some_value_not_present_in_config=0, it will crash
  when it attempts to log that.
diff: @@ -596,7 +596,8 @@ def run_redex(args):
  continue
  key = key_value[0]
  value = key_value[1]
  - log("Got Override %s = %s from %s. Previous %s" % (key, value, key_value_str, config_dict[key]))
  + prev_value = config_dict.get(key, "(No previous value)")
  + log("Got Override %s = %s from %s. Previous %s" % (key, value, key_value_str, prev_value))
  config_dict[key] = value
  log('Running redex-all on {} dex files '.format(len(dexen)))
  