Deleting items from "Other SIP Settings" removes them from from UI, but leaves them in sip_general_additional.conf

There appears to be a serious operational bug in the Asterisk SIP Settings module.  If you delete an item from "Other SIP Settings" that is not the very last item, it will remove all the remaining entries from from the UI, but leave them in sip_general_additional.conf

Here's how to reproduce:

Step 1:  Add four items to other SIP Settings:

1.  Temp1=Null

2.  Temp2=Null

3.  Temp3=Null

4.  Temp4=Null

Step 2:  Submit, and then apply changes.

Step 3:  Delete item #2 created in Step #1.   Leave items 1, 3, and 4.

Step 4:  For some reason, apply changes will appear even before you hit submit.  Not sure whether this is a bug, but it seems like it as I haven't yet saved anything.  In any case, save and then apply changes.  (you can also just apply changed if you prefer, it makes no difference to the bug).

Step 5:  Reload the page.  Items #3, and #4 will be missing from the "Other SIP Settings."  However, if you view /etc/asterisk/sip_general_custom.conf, those settings will still be present in the .conf file and still be impacting the operation of Asterisk.

Note that it you then add a new item to Other SIP Settings, the remaining items will now magically reappear.  

You will also get bizarre results if in Step 3, you delete the very first item, instead of the second.  If you do that , then the third entry will be duplicated and appear as item #4.