bug#49696: ‘guix build -S’ doesn’t work with ‘--with-commit’ & co.

[Ludovic Courtès]

Hi!

‘--with-commit’ & co. return a raw store file name, which breaks
‘guix build -S’:

--8<---------------cut here---------------start------------->8---
$ guix build guile-gcrypt --with-branch=guile-gcrypt=master -S
updating checkout of 'https://notabug.org/cwebber/guile-gcrypt.git'...
retrieved commit f8934ec94df5868ee8baf1fb0f8ed0f24e7e91eb
Backtrace:
          13 (primitive-load "/home/ludo/.config/guix/current/bin/guix")
In guix/ui.scm:
   2182:7 12 (run-guix . _)
  2145:10 11 (run-guix-command _ . _)
In ice-9/boot-9.scm:
  1752:10 10 (with-exception-handler _ _ #:unwind? _ #:unwind-for-type _)
In guix/status.scm:
    800:4  9 (call-with-status-report _ _)
In ice-9/boot-9.scm:
  1752:10  8 (with-exception-handler _ _ #:unwind? _ #:unwind-for-type _)
In guix/store.scm:
   658:37  7 (thunk)
   1320:8  6 (call-with-build-handler _ _)
   1320:8  5 (call-with-build-handler #<procedure 7f87670bbcf0 at 
guix/ui.scm:1154:2 (continue store things mode)> _)
In guix/scripts/build.scm:
   701:26  4 (_)
In srfi/srfi-1.scm:
    634:9  3 (for-each #<procedure show-derivation-outputs (derivation)> 
("/gnu/store/kjwr8cdz9s7a4y79pkz0zyvnwqmr9n5s-guile-gcrypt-f8934ec"))
In guix/ui.scm:
    908:2  2 (show-derivation-outputs _)
In ice-9/boot-9.scm:
  1685:16  1 (raise-exception _ #:continuable? _)
  1685:16  0 (raise-exception _ #:continuable? _)

ice-9/boot-9.scm:1685:16: In procedure raise-exception:
Throw to key `match-error' with args `("match" "no matching pattern" 
"/gnu/store/kjwr8cdz9s7a4y79pkz0zyvnwqmr9n5s-guile-gcrypt-f8934ec")'.
--8<---------------cut here---------------end--------------->8---

Ludo’.