postgresql 9.5 upsert issue with nulls

Hello,

I'm having an issue with using the new UPSERT feature in Postgres 9.5

I have a table that is used for aggregating data from another table. The composite key is made up of 20 columns, 10 of which can be nullable.
Below I have created a smaller version of the issue i'm having, specifically with NULL values.

CREATE TABLE public.test_upsert
(
upsert_id integer NOT NULL DEFAULT nextval('test_upsert_upsert_id_seq'::regclass),
name character varying(32) NOT NULL,
status integer NOT NULL,
test_field text,
identifier character varying(255),
count integer,
CONSTRAINT upsert_id_pkey PRIMARY KEY (upsert_id),
CONSTRAINT test_upsert_name_status_test_field_key UNIQUE (name, status, test_field)
)
WITH (
OIDS=FALSE
);

Running this query works as needed (First insert, then subsequent inserts simply increment the count):
INSERT INTO test_upsert as tu(name,status,test_field,identifier, count) VALUES ('shaun',1,'test value','ident', 1)
ON CONFLICT (name,status,test_field) DO UPDATE set count = tu.count + 1 where tu.name = 'shaun' AND tu.status = 1 AND tu.test_field = 'test value';

However if I run this query, 1 row is inserted each time rather than incrementing the count for the initial row:
INSERT INTO test_upsert as tu(name,status,test_field,identifier, count) VALUES ('shaun',1,null,'ident', 1)
ON CONFLICT (name,status,test_field) DO UPDATE set count = tu.count + 1 where tu.name = 'shaun' AND tu.status = 1 AND tu.test_field = null;

This is my issue. I need to simply increment the count value and not create multiple identical rows with null values.

Attempting to add a partial unique index:
CREATE UNIQUE INDEX test_upsert_upsert_id_idx
ON public.test_upsert
USING btree
(name COLLATE pg_catalog."default", status, test_field, identifier);

However this yields the same results, either multiple null rows being inserted or "ERROR: there is no unique or exclusion constraint matching the ON CONFLICT specification" messages being returned when trying to insert.

I already attempted to add extra details on the partial index such as WHERE test_field is not null OR identifier is not null, however when inserting I get the constraint error message.

Any suggestions would be appreciated, thanks!

-Shaun
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