If the attachment on the cloned test step got deleted, the original would also get deleted 

When clone a test step with attachments and then edit and delete the attachment of the new issue, the original attachment is removed as well. 

Steps to reproduce:

1. On a test case, create a new step with an attachment
   2. Clone this step
   3. On the clone step, click on it, so it is in the edit mode
   4. Delete the attachment on the clone step
   5. On the pop-up window, uncheck the box for remove attachment from Jira issue
   5. Refresh the page
   6. Observe the original attachment is also deleted

Workaround: Delete the attachment in read-only cell mode, i.e., click directly on the delete button instead of clicking in the step to edit.