In the Create New Sub-Execution dialog, cleaning the Fix Version field is erasing the content of the dialog

Short Description: In the Create New Sub-Execution dialog, cleaning the Fix Version field is erasing the content of the dialog leaving the Create button enabled.

Steps to Reproduce:

1 - Navigate to a Story issue with Tests on it

2 - Click to Create a new Sub-Execution

3 - In the dialog, clean the values of the field Fix Versions or just to BackSpace key on the field

Actual Result: All the content of the dialog is erased leaving just the action buttons enabled. The Sub-Test Execution is still created.

Expected Result: Not content should be erased and only the Fix Version fields should be cleared.