Backend: (🐞) 'CI/CD variable expression' doesn't work when bare variable (`$a`) on left hand side of or (`||`) operator

Something seems busted when writing a variable expression with an || operator that has a bare variable check($a) on the left:

stages:
  - test

variables:
  a:
    description: "hi"
  b: '1'

c1:
  stage: test
  rules:
    - if: "$a || $b == '1'" # doesn't run
  script:
    - echo hi

c2:
  stage: test
  rules:
    - if: "$b == '1' || $a" # does run
  script:
    - echo hi

According to the docs/spec you never tested it on the left hand side.

Infinity seat client I think.