Fix #1967 : IndexError when trying to open a non-json conf file

deluge/config.py

@@ -442,7 +442,7 @@ what is currently in the config and it could not convert the value
                 if self._save_timer and self._save_timer.active():
                     self._save_timer.cancel()
                 return True
-        except IOError, e:
+        except (IOError, IndexError), e:
             log.warning("Unable to open config file: %s because: %s", filename, e)
 
         # Save the new config and make sure it's written to disk