bug#49916: etc/committer: backtrace on gexp

[Sarah Morgensen <iskarian@mgsn.dev>]

Hello Guix,

(Ricardo, I've Cc'd you since it seems etc/committer.scm is mostly your
work.)

It looks like etc/committer.scm is choking on gexps on core-updates-frozen:

--8<---------------cut here---------------start------------->8---
~/guix-cu-frozen [env]$ etc/committer.scm
ice-9/read.scm:126:4: In procedure read-expr*:
gnu/packages/games.scm:13005:11: Unknown # object: "#~"
--8<---------------cut here---------------end--------------->8---

...and this is the offending package:

--8<---------------cut here---------------start------------->8---
(define-public 0ad-data
  (package
    (name "0ad-data")
    (version "0.0.23b-alpha")
    (source
     (origin
       (method url-fetch)
       (uri (string-append "https://releases.wildfiregames.com/0ad-"
                           version "-unix-data.tar.xz"))
       (file-name (string-append name "-" version ".tar.xz"))
       (sha256
        (base32
         "04x7729hk6zw1xj3n4s4lvaviijsnbjf5rhzvjxlr5fygvg4l6z1"))
       (modules '((guix build utils)))
       (snippet
        #~(begin
            (for-each (lambda (name)
                        (let* ((dir (string-append "binaries/data/mods/" name))
                               (file (string-append dir "/" name ".zip"))
                               (unzip #$(file-append unzip "/bin/unzip")))
                          (invoke unzip "-d" dir file)
                          (delete-file file)))
                      '("mod" "public"))
            #t))))
    (build-system trivial-build-system)
--8<---------------cut here---------------end--------------->8---

I think with the changes from new style inputs, gexps in packages are
going to become more common, so etc/committer.scm should support them.

WDYT?

--
Sarah