BUG #15260: When saving json object to a json column bigInteger valueis saved wrong

The following bug has been logged on the website:

Bug reference:      15260
Logged by:          Uri Parush
Email address:      urip@ensilo.com
PostgreSQL version: 9.6.0
Operating system:   windows 10
Description:

Hi, I think I found a bug in PostgreSQL json column type.
I created the next table:
CREATE TABLE public."Dummy"
(
   json json
)

And insert the next data:
INSERT INTO public."Dummy"(
    json)
    VALUES (
'{ "ID": 9059650307334996772}'
);


The data that was saved was incorrect:
{"ID":9059650307334997000}

Looks like PostgreSQL round the number in the insertion.