Re: BUG #15055: parenthesis disappear

The following bug has been logged on the website:

Bug reference:      15055
Logged by:          Andrei Mitran
Email address:      andrei@ivc.com
PostgreSQL version: 9.6.1
Operating system:   centos
Description:

alter table ivc.merit_matches
  add constraint priced_or_slotted_job
  check ((survey_code is null and slot_job_code is not null) or
         (slot_job_code is null and survey_code is not null));
results in:
Check constraints:
    "priced_or_slotted_job" CHECK (survey_code IS NULL AND slot_job_code IS
NOT NULL OR slot_job_code IS NULL AND survey_code IS NOT NULL)

What happened to my parens around the and conditions? I am not aware of any
precedence of and over or - Am i misinformed?