Description of problem:
In a run view, select no case and click the the "Add" of "Bugs" label, the reaction is that the input box for bug id comes out.
Then if you choose cancel, there comes up a confirm box warning "Please specify bug ID".
If you input a valid bug id, there is a confirm box warning "Please specify only integers for bugs, caseruns(using comma to seperate IDs), and bug_system. (DEBUG INFO: invalid literal for int(): )".

Version-Release number of selected component (if applicable):
TCMS 3.4.1-2 - stage 

How reproducible:
100%

Steps to Reproduce:
1.Enter into a run.
2.Choose none cases.
3.Click "Add bug" button
  
Actual results:
When choosing none cases, the input box for bug id still comes out.
Then if you choose "cancel" button in the box or input nothing and click the "add" button, there comes up a confirm box warning "Please specify bug ID".
If you input a valid bug id and click the "add" button, then there comes out a confirm box warning "Please specify only integers for bugs, caseruns(using comma to seperate IDs), and bug_system. (DEBUG INFO: invalid literal for int(): )"

Expected results:
After clicking "Add bug" button, a warning box should come out.

Additional info: