3.12.0 BC break on json column

[TakTaki]

Q	A
Bug report?	yes
Feature request?	no
BC Break report?	yes
RFC?	no

Since 3.12.0, the serialization of json changed, introducing what I think is a BC break.
I have a Doctrine column define as follow
@ORM\Column(name="value", type="json", options={"jsonb"=true}, nullable=true)
Before 3.12.0, when the value stored was equals to true, the serialized value was true.
In 3.12.0 it now returns {true}.

I think this is link to recent changes here. I commented this line and got what I expected, ie true

Steps required to reproduce the problem

1. @ORM\Column(name="value", type="json", options={"jsonb"=true}, nullable=true)

Expected Result

• true

Actual Result

• {true}

[TakTaki]

Just saw that I'm not alone and a PR is already pending #1295

[goetas]

Done in #1295