BUG #14297: ON CONFLICT fails

The following bug has been logged on the website:

Bug reference: 14297
Logged by: Ilies Radu
Email address: iradu(at)unix-world(dot)org
PostgreSQL version: 9.5.4
Operating system: Any
Description:

Hi,

I have an issue with the newest ON CONFLICT clause in newest PostgreSQL
9.5.

If I do:
INSERT ... ON ONFLICT ...
works ok.

But if I do
UPDATE ... ON CONFLICT ...
fails always (said feature not implemented !!)

By example I need:
UPDATE mytable SET some_unique_key = 'some_existing_value' ON CONFLICT DO
NOTHING

Is this a bug or a not implemented feature (UPDATE ... ON CONFLICT)

If is not implemented I hope to see it soon as also UPDATES can generate a
conflict not only inserts.

In mysql there is:
INSERT IGNORE
UPDATE IGNORE

In postgresql 9.5 I only can see now:
INSERT ON CONFLICT DO NOTHING
*** UPDATE ON CONFLICT DO NOTHING *** Fails always !!!

Regards,
Radu