ON server validation setForm does not work s expected

Steps to reproduce

1. Attach the following behaviour to TextFieldA

def desc = getFieldById(IssueFieldConstants.DESCRIPTION)
def formField = getFieldByName("TextFieldA")

desc.setFormValue(formField.value)

Now every time you write something to TextFieldA, the behaviour copies the value to the description, everything works as expected.

2. Create an issue and navigate to the issue view page for that issue
3. Click create, so now in the background there is the issue view page in in the foreground the create new issue form
4. Now submit the issue without summary (in order to force a server side validation failure)
5. write something to TextFieldA, the description is not getting updated, as someone would expect.