Kernel parameters form resets to previous value after save

[Alberto Donato]

When editing global kernel parameters from the Settings -> kernel parameters page, the form resets the text field to the previous value after saving.

E.g.:

- form is empty, type in some parameters and save
- form shows empty again with save button ticked
- reload the page, form shows the previously entered text
- remove the text, save
- form shows previous text

Values are correctly saved, but displayed value is wrong.