NZB Search: settings not saved

[achilleus68]

I have an issue with the 'Search Settings', tab 'NZB Search'

Settings for connecting to SABnzbd are not saved. After entering and saving, I can connect to SABnzbd (according to the respons). On reload of the page, the settings are gone.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Search Settings', tab 'NZB Search'
2. Select 'SABnzbd'
3. Enter SABnzbd username / password / api key
4. Save
5. Test SABnzbd settings > Success
6. Reload page
7. Go to 'Search Settings', tab 'NZB Search'
8. SABnzbd password / api key are empty

Demo https://streamable.com/9ynfy

Expected behavior
'NZB search' save

Log warnings
2018-11-17 20:01:25 WARNING APIv2-Thread_2 :: [a1d899b] Config patch ignored {u'clients': {u'nzb': {u'sabnzbd': {u'testStatus': u'Authentication failed. SABnzbd expects '{"auth": "apikey"}' as authentication method, API Key Required'}}}}
2018-11-17 20:01:08 WARNING Thread_1 :: [a1d899b] Sabnzbd's API key is missing

Medusa (0.2.12 (2018-11-16)):

OS: Debian (Raspberry Pi B)
Branch: master
Commit: master

May be related to #5642 , but that one is closed