(require 'json)

(defun vc-pijul--out-json-read (command &rest args)
  "Run `pijul COMMAND ARGS...' and return standard output as a string.
The exit status is ignored."
  (with-temp-buffer
    (apply #'vc-pijul--out-ok command "--output-format" "json" args)
    (goto-char (point-min))
    (json-read)))