'Payment' field has a bugs in edit mode

[leelokas]

• Create a Paid vacation/Study leave request
  • Select "With next salary" as the payment type
  • Save
• Open edit view with the saved request
  • It shows "Before vacation" as the selected payment type (!)
• Do not make any changes and "Save"
  • Payment field is now empty (!)
• Open edit view with the saved request
  • It shows "Before vacation" as the selected payment type (!)
• Do not make any changes and "Save"
  • Payment field is correctly saved as "Before vacation"

If user/admin clicks on the payment dropdown and selects the option by hand then everything works correctly. But if user/admin doesn't change the dropdown initial value then something else is saved.