Note that in order to test and verify this you will need to force an error in the configuration. To do so manually perform the following update in the database:

  update vdc_options set option_value='secure=bool,port=int,slot=int' where option_name='VdsFenceOptionTypes'

Then restart the engine, and once it is running again request the API capabilities resource:

  GET /ovirt-engine/api/capabilities

That used to fail but should succeed now, and the following error message should appear in engine.log:

  ERROR: No type specified for fencing option "encrypt_options".

Moving back to MODIFIED, although patch was merged into 3.6.5 earlier than the build started, it's not included ...

As far as I understand there is another 3.6.5 engine build, so moving back to 3.6.5.

Verified with:
rhevm-3.6.5.3-0.1.el6.noarch

engine=# update vdc_options set option_value='secure=bool,port=int,slot=int' where option_name='VdsFenceOptionTypes';

engine=# select * from vdc_options where option_name='VdsFenceOptionTypes';
 option_id |     option_name     |         option_value          | version 
-----------+---------------------+-------------------------------+---------
       655 | VdsFenceOptionTypes | secure=bool,port=int,slot=int | general
(1 row)

# service ovirt-engine restart

https://10-34-61-187.rhev.lab.eng.brq.redhat.com/ovirt-engine/api/capabilities returns correct xml

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2016-0661.html