challenge: Really exit with non-zero upon hash mismatch.

Reported by John Darrington.

* guix/scripts/challenge.scm (guix-challenge): Add an explicit 'exit'
call when ISSUES is empty.
* scripts/guix.in: Add comment about 'exit'.
* doc/guix.texi (Invoking guix challenge): Mention the behavior and exit
code.

1 files changed, 5 insertions, 0 deletions

diff --git a/scripts/guix.in b/scripts/guix.in
index 8f2d8a6433f..5d6921dd09d 100644
--- a/scripts/guix.in
+++ b/scripts/guix.in
@@ -64,4 +64,9 @@
       (apply guix-main (command-line))))
 
   (maybe-augment-load-paths!)
+
+  ;; XXX: It would be more convenient to change it to:
+  ;;   (exit (run-guix-main))
+  ;; but since the 'guix' command is not updated by 'guix pull', we cannot
+  ;; really do it now.
   (run-guix-main))