Not all valid sub-tasks created if invalid sub-task specified

[Don Brown]

Repro Steps

Select "Create Sub-Tasks" from View Issue Page
Create sub-tasks in the following order:
    Valid sub-task(s) - e.g. "1"
    Invalid sub-task(s) - e.g. subtask with more than 255 chars
    Valid sub-task(s) - e.g. "2"
Submit list of sub-tasks
Refresh the View Issue page

What Happens

Only valid sub-task(s) specified before invalid sub-task(s) are created - in above example, only "1" is created
Error shows for invalid sub-task

The above would lead users to believe that no sub-tasks were created due to error.